Constipation occurs when something slows the rate of your bowel movements. Whatever is normal for you is your base point. Someone who normally has a bowel movement every day is constipated if he hasn't had one in three days, while someone who normally goes every three days is fine at that pace. The key to getting things moving along again is fiber. Fiber is the substance in certain foods that passes directly through your digestive tract without being digested or used by your body.