Hunter S. Thompson on finding your purpose:

As I see it then, the formula runs something like this: a man must choose a path which will let his ABILITIES function at maximum efficiency toward the gratification of his DESIRES. In doing this, he is fulfilling a need (giving himself identity by functioning in a set pattern toward a set goal) he avoids frustrating his potential (choosing a path which puts no limit on his self-development), and he avoids the terror of seeing his goal wilt or lose its charm as he draws closer to it (rather than bending himself to meet the demands of that which he seeks, he has bent his goal to conform to his own abilities and desires).

[via Brain Pickings, of course]