Getting six pack abdominals takes a lot of hard work and exercise. Many experts will suggest crunches when trying to achieve this goal. The rectus abdominis is what you are working when you are doing crunches. The bicycle exercise is also very effective when working these muscles .
The more you exercise and the greater the intensity, the faster the muscles will tone. it is very important to exercise within moderation to prevent any damage.
Some people are genetically predisposed to be able to be in better shape than others. Some people are naturally lean while others have a tendency to carry more fat. Men are usually more lean than women so it generally easier for them.
Keep in mind that people like Brad Pitt have professional trainers who tell them exactly what to do. It's not any easier for them, they still have to work at it, but they have the money to pay someone to tell them exactly what and how many to do.