So here's the cosmic joke. If the goal was your life purpose, and you achieved it, what would happen? You'd stop. But once you stop, there is no precession, no side-effects - and it's the side -effect, not the goal, that is your life purpose.
Humans are MEANT to be IN MOTION.
Fuller looked at the fact that NO ANIMAL HAD TO EARN A LIVING. They are just doing what they are supposed to do. If they do that, then nature & God looks after them.
http://www.relfe.com/life_purpose.html
How To Know What Your Purpose In Life Is