What to do with my life

I'm beginning to seriously doubt that I'll ever figure out what to do with my life. I thought I had a plan, up until today, only to have the foundations of what I'm doing thrown into question. Sorry I can't be more specific--those of you who know me can e-mail me, and I'll give you an answer--but this is a public forum, after all.

I'd like to address more generally the question of purpose in life. Is it possible to determine your purpose in life? I'd like to propose a theory--that it's not possible. Think about it--purpose implies a why for something, a reason for being. But the why for something is really only evident (if it's ever evident at all) in hindsight, when you can look back and say, "Oh, that's the reason that happened!" This is how it works in scientific experimentation--you experiment, test your results against a control, then evaluate the variable as it pertains to the cause of your experiment.

Only in life, you have no "control," no "second experiment." You can look back, make reasonable guesses about why something happened, or why some decision was made, but to look into the future, figure out a course of action, and say, "yes, this is the purpose to which I must dedicate my life," this is something that seems impossible to me.

Instead of purpose, which is how I realize I've been thinking about things recently, I think I need to re-frame my question, to read, "what am I called to do with my life?" This question is becoming more real to me, as I contemplate my future and my past.