Bodybuilders often have the most extreme six packs
The key to six pack abs is an extremely low body fat level. A lot of guys can do the ab work necessary to develop a high level of muscle size, but the dietary restriction required to make the muscles visible is often beyond the discipline level of most people.
Gymnastic moves are a great way to develop washboard abs
Another benefit of having a Six Pack: Women LOVE IT!!
Women can have a Six Pack too!!
Far too many guys have a keg rather than a six pack :-) This is what a "Before" picture looks like