Usually, when people travel they do a lot of sitting. When you sit too long circulation slows down, Not drinking enough water will cause the system to clog up, or slow down. When people travel they drink less water, as they usually cannot get up and go to the bathroom when the urge comes and being in that situation is scarry, I have been there on a jet airplane especially on take off. Then you have to hold it, or on a transit bus that has no bathroom, or the subway trains! Believe me, I always said to my husband when we lived in NY, that many people there must be constipated! Why, when you are out and about, it is quite impossible to find a bathroom when you need it. You either have to hold it, or go into a restaurant and order something to use their bathroom. That is one of the main reasons I will never live in the big cities anymore. It is very unhealthy to have to hold it. That helps make a sick colon, and a sick person!