The P90X is an extreme workout that aims to get you tone and fit within ninety days. This program claims to work by confusing the muscles, which includes using new muscles that are not used to being worked to great a fully toned body. This program is fast and can be very strenuous on your body. It is really designed for people who are relatively in shape already and are looking to tone up and get a great beach body. If you have pre-existing injuries in your joints, this program may also not be suited for you. The P90X workouts get intense very quickly, so you need to pay attention to your body while exercising so you do not over-do it and cause any unnecessary injuries to your body.