You cannot safely stop pooping completely
If you mean frequent bowel movements, see a doctor
Drink enough water
Eat more soluble fiber if stools are loose
Eat less greasy, spicy, or trigger foods
Avoid excessive caffeine and alcohol
Review medications and supplements with a clinician
Use anti-diarrheal medicine only if a doctor says it is safe
Seek urgent care if you have severe pain, blood, fever, dehydration, or black stools