Marzia Prince—Healthy Housewife, fitness trainer, and core building master—brings us 3 variations of the abdominal bicycle. First up is the half bicycle. Lay down on your mat, facing the ceiling. Bring up one leg and the opposite arm with your hand lightly behind your head. Bring both your elbow and your opposite leg together while squeezing your muscles and tucking your stomach. Do the other leg and arm too with a set number of reps or time yourself. Next, the full bicycle. Both legs and arms will be up for this one, both hands behind your head. Alternate bringing opposite elbows and legs together, opening and squeezing, much like a bicycle. Last, do the standing bicycle. This is exactly like the full bicycle, but you will be standing for more ab crunching power. Don't forget to do each side and start toning those abdominals and building your core strength today.