Well I'd have to give a scenario.

Let's say that there is a boy, and as he develops, he discovers that weaving baskets is unhealthily entertaining and fulfilling. Then one day he comes across an elderly woman who is sitting in a park, lonely and sad. He decides to weave her a basket and fills it with wildflowers. The woman becomes overjoyed and finds herself looking forward to a new day, rather than resenting the mere thought.

The boy picks up on her change in outlook on life and realizes what makes him happy can make others happy. He begins repeating the action of finding unhappy souls and weaving them prescious gifts with love. In turn, the once miserable people begin to share smiles and general good vibes with others... Spreading around love. As his experiment continues to be successful he realizes that this is why he's "here"... This is his purpose. He becomes the balance needed to bring a sense of purpose back to others.

He decides on his own what his purpose is. He made it up, so to speak.