Lie on your back with your fingers behind your ears and your legs raised at ninety-degrees at your hips and knees. Think of it like sitting in a chair while lying on your back.

The idea with the bicycle is to try touching your left elbow to your right knee and your right elbow to your left knee. To do this you will crunch upward while twisting at the waist to send one of your elbows forward while drawing the opposite knee toward your elbow.

TIP: Try not to help close the gap between your elbow and knee by just swinging your elbow over. Instead, really use your abs (obliques) to twist your torso to help close the gap.

This is effectively a Leg-Lift and a Crunch combined. Lie flat on the floor with your legs straight out and feet together and your arms over your head.

Lift your legs to about ninety-degrees from the floor by engaging your lower abs while simultaneously rotating your arms to be along your sides and doing a crunch. The result is your legs are almost straight up in the air, your upper back is several inches off the ground, and your hands are at the ground near your glutes.

Get into a crunch position by lying on your back, your fingers behind your ears and your feet flat on the floor close together. Now, let your knees drop to the sides while keeping your feet together. The result is that the souls of your feet are touching each other with your knees at or near the floor. Do this exercise from this position.

Raise your shoulders off the ground several inches by tightly engaging your abs. Resist the urge to tighten the muscles at the front of your hips and this will be a very effective workout.

Lie flat on your back with your legs pointed straight in the air. Place your hands at your side near your glutes for balance.

Engage your upper abs to draw your tailbone and a little bit of your lower back off the floor. As you are rising, draw one of your hips inward by contracting your oblique muscle on your side. Visualize trying to pull your hip toward your ribs. Alternate the direction of your twist with each rep.

TIPS: Beginners may find that they are placing a lot of pressure on their hands to help rise off the floor. As you become more advanced, use your hands very lightly and only for balance so that the entire motion is accomplished by your abs.

Lie on your back, bend your knees at ninety-degrees with your feet flat on the floor and place your fingers behind your ears.

A crunch is an exercise involving a small amount of movement. As you tighten your abs, your shoulders should come off of the floor 3-5 inches. Keep your chest and face pointing straight up toward the ceiling during the motion. Your abs should collect together very tightly as if to draw your lower ribs toward your pelvic bone.

TIP: Beginners may find it easier to have their arms at their sides and can even try to tap their heels at the top of the crunch. At an intermediate level you can cross your wrists at your chest. Advanced crunches are with your hands above shoulder level (e.g. behind head).

Get into position as if doing a crunch but with your fists meeting each other right at your chin – almost as a boxer would guard their face.

Now, do a crunch, pause at the top briefly and then rotate your torso to one side. As you twist, really squeeze that oblique muscle that is causing you to rotate. After you reach the end of the twist, return to center and then lower to the start position. Repeat and twist to the other side and so on. Remember: up, pause, twist, center, pause, down.

The double crunch is a crunch and a reverse-crunch combined. Get into position on your back with your legs up and bent as if sitting in a chair (but while lying down) and your fingers behind your ears.

The idea now is to raise your tailbone off of the floor like in a reverse-crunch at the same time you raise your shoulders off of the floor like in a crunch. At the top of this movement your weight will be on your middle back.

The overall movement should generally be minimal as you are more trying to tighten and collect your abs than to create a large motion. However, advanced levels can draw this exercise into a larger motion.

Lie on your back and raise your feet off of the floor with your legs bent as if sitting in a chair (but while lying down). Your thighs should be perpendicular to the floor. Place your hands behind your ears.

From this position, do a crunch by collecting your abs tightly and raising your shoulders 3-5 inches from the floor. Keep your chest and face pointed toward the ceiling.

TIP: Concentrate on keeping your legs perfectly still and in position while doing this exercise. This small detail will increase the intensity and effectiveness of this exercise as your body works to stabilize your lower half while your upper half is in motion.

Lie on your back with your feet flat on the floor and spread about shoulder width apart or more. Hold your hands open and loose at your chest as if you just caught a football and were drawing it in.

Visualize a ball coming toward you on the outside of one of your knees. Reach your hands out and stretch toward that ball to catch it. If you are reaching properly, your arms will be outstretched with your hands along the outside of your knee, your shoulders off the ground and your torso twisted slightly. Lower back to the starting position and reach to the other side. Do not sit up. The motion should be about that of a crunch with your lower back still on the ground.

Lie your entire body flat on the floor with your legs straight out and your hands on the floor at your glutes for balance.

While keeping your entire upper body flat on the floor, engage your abs to draw your straight legs up off of the ground until they are straight up in the air, perpendicular to the floor. Lower your legs back to the start position but without resting your heels on the floor (hover about an inch from the ground).

Beginners may need to lower their legs only about half way to the floor before raising them up again. As you gain strength you will be able to lower your legs closer and closer to the ground.

Lie on one side with your ankles overlapping and your body bent slightly at the waist for balance so you will not tip over. Rest your lower hand on your waist while your other hand is behind your ear like for a crunch (your elbow should be toward the ceiling).

Now, try to pull your ribs toward your hip by engaging your oblique. While doing this you should be pulling your ankles and knees as well as your shoulder you are lying on off of the ground. Use your hand that is on your side to feel for your oblique tightening.

This is an advanced exercise. Beginners may need to place some weight on their elbow and use it as a pivot point. It may also take some time before being able to pull your knees from the ground, but until then, squeeze your obliques as tight as you can to take as much weight off your knees as possible.

Lie on your back with your legs and feet pointed straight up in the air and your arms straight out to your sides. You will need your arms out for balance.

Lower your legs slowly by letting them fall directly to one side. Keep both of your shoulders on the ground and allow your body to twist at the waist. When your feet are a few inches from the ground, use your abs to rotate your legs straight back up in the air. Now lower your legs to the other side and so on.

While facing the floor, support your extended body off of the ground with only your elbows and toes. Your elbows should be on the floor directly below your shoulders and your feet should be close together.

Keep your body as straight as you can from head to toe. This exercise will use your abdominal muscles to keep your body from sagging toward the floor. Keep your abs tight and solid.

TIP: To intensify the plank exercise, move your elbows further ahead so that there is more distance between your elbows and toes.

Lie on your back with your legs and feet pointed straight up in the air and your arms along your sides with hands near your glutes.

Engage your upper abs to pull your tailbone and lower back from the floor. Think of it like trying to reach your toes to touch the ceiling. Squeeze your abs really hard at the top to try to get just another quarter inch closer to the ceiling.

TIP: Beginners may find that they are placing a lot of pressure on their hands to help rise off the floor. As you become more advance, use your hands very lightly and only for balance so that the entire motion is accomplished only by your abs.

Lie on your back with your feet flat on the floor and a little more than shoulder width apart. Your arms should be outstretched and your hands pointing right between your knees.

Do a crunch by tightening your abs and pulling your shoulders and upper back 3-5 inches from the floor. As you rise your hands will pass, or push through, right between your knees.

This is basically a simpler version of a crunch. Advanced persons can make this more difficult by pausing at the top for two counts while squeezing their abs as tight as possible.

Get into position on your back with your legs up and bent as if sitting in a chair while lying down and your hand resting across your chest.

Use your abs to pull your knees tightly toward your chest. Your tailbone and a little of your lower back should come off of the ground as your pelvis is being pulled inward. Be sure you are pulling with your abs and not simply rotating your legs at your hips.

A rollback is essentially a sit-up in reverse. Your starting position is sitting on the ground with your feet flat and your torso up off the ground. Place your hands behind your ears.

Now, tighten and collect your abs together and roll slowly onto your back. Keep your abs tight through the whole motion. Your back should have a slight curve to it the whole time, so concentrate on trying to place one vertebrae at a time on the ground as you roll back. Do not straighten your back or you may cause excessive strain as well as cause your abs to not work as hard.

After you take about three counts to roll back, return to the start position by doing a basic sit-up (you can assist yourself on the way up in order to avoid the energy cost of a full sit-up). Then collect your abs tightly and roll back again. You can put your toes against a wall or under something to help keep your balance, but try to use that assistance as little as possible during the roll-back movement of the exercise.

Sit on the floor with your feet flat and your torso about 45 degrees from the ground. You will need to keep your abs engaged to hold this angle. Hold your fists together near your chin as a boxer would hold their gloves.

While maintaining your 45 degree angle, twist your torso to one side. As you twist, focus on really squeezing your oblique that is causing you to twist. Now twist to the other side. You should be able to count about one second from one side to the other.

TIP: To intensify this further, slow the motion down and give a longer, more deliberate squeeze of the oblique at the extreme of each twist. Another option is to pause each time you reach the center position before twisting to the other side as demonstrated in the video.

This is a crunch with a variation, so start out in the crunch position.

Now, do a crunch as you normally would, but when you reach the top pause for a brief moment. Immediately after this pause, engage one of your side obliques so that your body will bend sideways. Your shoulders should stay the same distance from the floor as they swing to one side. After squeezing at the extreme of the bend, return to center, pause, bend the other way, return to center, and then lower. Up, over, over, down is one repetition.

Lie on one side with your ankles overlapping. Take your hand of the arm you are lying on and rest it on your waist. Your other hand should be behind your ear with your elbow pointed toward the ceiling.

Now, pull your ribs toward your hip by engaging your oblique abdominal muscle (side muscle). Doing this will raise the shoulder you are lying on off of the ground a few inches. Use your hand that is on your side to feel your oblique working. Be sure to pause at the top and squeeze that oblique to really make it work.

Beginners may use their elbow on the ground for assistance with balance and to also take some of the weight off of the movement.

Lie on your side in the same way you would prepare for a side crunch.

As you tighten your oblique to pull your should from the ground, lift your top leg straight up like it is going to meet your elbow in the middle. Remember to give an extra tight squeeze of the oblique at the top of this motion.

While lying on your side, support your upper body up off of the ground by resting on your elbow. Your feet to your hip should be at the ground and your torso bent slightly upward from resting on your elbow.

Raise your hip off of the floor all the way until your body is straight by tightening your oblique. Squeeze your oblique for a moment at the top and then lower your hip back near the start position. Do not rest your hip on the ground before raising back up – keep your oblique engaged the whole time.

While lying on your side, support your upper body up off of the ground by resting on your elbow. Your body should be perfectly inline and only your feet and elbow along with your forearm should be in contact with the ground.

This exercise will use your obliques to keep your body from sagging toward the floor. Keep your obliques tight and solid.

TIP: To intensify the plank exercise, move your elbow further ahead so that there is more distance between your elbow and toes.

Lie on your back, bend your knees at ninety-degrees with your feet flat on the floor and place your fingers behind your ears.

Raise your entire torso from the ground so that you are sitting almost straight up and your chest is very near your knees. Find a spot on the ceiling and stare at it as you go up so that you do not tuck your head in. Try to use as much abs and as little legs as possible as you do a sit-up.

Beginners may use something to hold their feet down like a friend or a weight. Intermediate persons can simply put their toes against a wall and use the friction to keep their toes from coming up. Advance persons may decide to not use any assistance to keep their feet down at all.

Sit on the floor with your legs straight and spread wide apart. You should be sitting almost upright, but lean back just slightly so you are not exactly straight up from the floor. Hold your arms to the side like you are flexing your biceps or like you have a stick across your shoulders that your are also holding in your hands.

Twist your torso far to one side while squeezing your front abs as well as the oblique causing you to twist. Pause slightly and then return to center. When you reach center you can release your abs for a moment and then reengage for the other direction.

Although this is a seemingly easy exercise, it is very effective. Be sure though that you are squeezing your abs to accomplish this motion.

Lie flat on the floor with your legs straight out and feet together and your arms over your head.

Lift your legs to about forty-five degrees from the floor by engaging your lower abs while simultaneously rotating your arms forward and reaching for your toes. While reaching for your toes you should accomplish a crunch with your shoulders several inches from the ground. Lower yourself back near the start position, but do not rest your heels on the floor. This will help keep your abs engaged during the whole set and much more effective.