Senna: This is a laxative which aids in emptying the intestines.
Cascara Sagrada: Encourages movement of the bowels and tones muscles of the intestinal tract. Enhances excretion of bile and corrects congestion of bile ducts. Aids chronic indigestion and chronic liver disease.
I like cascara sagrada because it does more internally and has other benefits. the key is to change off.
Also, our physical movements move our intestines. If we are sitting on the couch our insides are not moving. Simple walking helps things move through.