There are plenty of simple ab exercises that you can do on your own, in your house, with no special equipment required.

Most of the best exercises for strengthening the ab muscles are crunches. Crunches are exercises where you bring your body right forward, curling upwards to bend yourself into a tight V shape. There are very many variations on crunches.

One of the most popular is the exercise ball crunch, which is where you lie back onto an exercise ball, and then do a crunch slowly, without the ball moving. This allows you to keep a good crunch speed, as well as supporting your back while you crunch.

Another good method is the full crunch, where you extend out your legs and then put your hands behind your head. As you pull yourself up with your hands, push outwards with your legs. If it is done right, this will exercise both your upper and lower body.

You might also try the reverse crunch (sometimes known as a V-up), where you lie on the floor, put your legs in the air, and then instead of bending up towards your legs, you bend your legs back towards you. This has the same effect, but is less strenuous, as you are lifting less weight.

A word of warning: as ab exercise becomes more popular, some companies are trying to cash in by hawking ab exercise machines and tools those little frames that you put around yourself while you exercise, and that rock you back and forward. However, research has shown that there is no difference between the benefits of using these machines and just doing a normal ab crunch. There is, however, certainly a very large difference in price (the difference between free and very expensive), so its best to just avoid them altogether.