I’m 21 and I’ve known I wanted to write for a living for years. I’ve changed my mind about what form I wanted that to take… went to college for journalism but wanted to try screenwriting, but stuck with journalism, found types of it that I liked, and now I’m enjoying it and plan to keep doing it for a living. I wouldn’t say I made up my mind about wanting to “do it for the rest of my life” until maybe a year and a half ago, and I still want to do other things in there as well: magazine articles get made into screenplays often, and it’d be a thrill if that ever happened, and of course sometimes they get made into books, and I’m sure I’d like to attempt a few of those along the way.
37 and not a clue.
And I kind of like it that way. The idea of having the same job for the next 30 or 40 years doesn’t really appeal to me. Heck, I’m still surprised when I look up to discover I’ve worked someplace for 5 years.
Unless I can get a job being paid to explore and travel for the Travel Channel. I think I could do that for 30 years. 
When I grow up I want to be God. Or a Truck Driver.
Actually, I’m going back to college (at the ripe 'ole age of 37) for yet another career change. I’ll be getting my Master’s in Secondary Education this time around. Perhaps this makes me a Professional Student.
I fell into it; I decide to get my non-degree requirements out of the way early in college, and decide to major in an unexpected field.
Along the way, I decided to pick up a 2nd complemantary major. That’s the field I ended up in.
Thirty here and I’ve never had a real job yet. I think I’ve finally decided which direction i want to go though 
I think I see a pattern here.
Yes, FilmGeek I’d have to agree with you. There definitely seems to be a pattern. So, thanks to all… I feel better for being 29 and only beginning to figure it out.
I’m 36. I have a wife of 11 years and a 5 year old son. We have owned our house for over 10 years, and I have been at my current job for almost 6 years now. So I am a pretty stable guy.
One year ago today, I would have said that I figured it all out shortly after I got married, or when my son was born.
One year ago, I was a non-practicing Christian. Today I am a devoted Catholic who is very involved in his church.
One year ago, I was a computer geek who would, given the opportunity, spend 16 hours a day surfing the net, playing games, whatever. Today I own 2 horses and spendevery weekend (and parts of most weeks) feeding and grooming, mucking out stalls, building fences, and occasionally actually getting to ride.
No earth-shattering changes, and nothing profound, but I can safely say that one year ago, what I wanted to do with the rest of my life bore no resemblance to what I am doing today. And I am much happier now than I was then.
So I guess my point is, I still haven’t decided. I don’t think I ever will. I don’t want to exclude any possibilities.