In order to keep things interesting and progressing, to keep the blood flowing and prevent stagnation in different parts of the body, life has to be somewhat shook up every so then.
I see life as a jug of unfiltered apple or orange juice: after a while, the pulp, which contains all the delicious fruit, will settle to the bottom if you don’t shake it, and the liquid on top will taste watered down and flat, never reaching its full flavor potential. If it tastes “OK” or “so-so,” it won’t be something to write home about.