One way is to ensure you are drinking enough water. This means limiting your caffeine intake and limiting drinking alcohol both can lead to dehydration. Additionally If you are taking any pain medication that has an opiate base, like codeine or morphine for example, it makes having a bowel movement more difficult and means you should be drinking additional water to help you out.

Second, eat a high fiber diet. Fiber helps with regularity and if you do not get enough fiber in your diet then a drink like Metamucil can help.

If these do not work then it is best to speak with your doctor to see what else can help.