How do i prevent anal fissures and hemorrhoids? are there certain exercises i can do to help prevent them?

Exercises:no: Anal fissures are caused from an overly tight anal sphincter muscle: that's the muscle that keeps the anus closed and relaxes when you poop. Keeping your stool soft can prevent hemorrhoids, by eating lots of fiber, drinking lots of water, exercising. Sometimes anal fissures just happen, even if you do all that. There are some prescription ointments that can relax the muscle & heal: see a doctor.

Diet not exercise: Anal fissures are caused by passing large, hard stools. Hemorrhoids are due to straining to pass hard constipated stools, straining, heavy lifting... Be sure you are drinking plenty of water daily and getting plenty of fiber in your diet. Exercise will not prevent either.