Fiber is one of the things most normal people don't get enough of. People who workout alot tend to more food than normal people and lots of those calories come from low fiber foods which can make their diets even worse. So be smart and make sure you are getting lots of fiber in your normally scheduled diet.
Whole fruits, whole grains, and beans will go along way towards meeting your daily need. Fortunately, supplements are very easy to bring you to 100%.
If you are severely fiber deficient, make sure you work up slowly to the 100% recommended amount you need for optimum health. While all your buddies are experiencing digestive system traffic slowing down their absorption, your system will be running like a well oiled machine.
There are many things that people call "fiber" that really are not. Get wheat dextrin or traditional psyllium as your primary supplement source.