Doing workout forces your abs to develop because the exercises you perform helps in building up the rectus abdominis. The rectus abdominis is the long muscle that extends vertically along the length of your abdomen. When you conduct these simple exercises, you will be working on all the muscles around your abdomen that aids the development of six packs. Exercising the muscles that make up your abdomen can help increase muscle mass to achieve six packs. There are many types of exercises that you can find on different books. But in order for you to work towards your desired result, you will need to correctly follow this 21 days six packs workout guide which I have used my numerous years of experience as a fitness trainer to write.