Two things, either one would make me perpetually happy.
1> Professional novelist. If I can write books, and sell them, while making enough to earn a decent living while maintaining a reasonable lifestyle, that's enough for me. If I can pay the bills, afford groceries, and buy 1 new game a month, I'd be happy. Although, getting along as a writer is nigh-impossible, according to everyone I talk to. So I expect to spend a lot of time doing odd-jobs and quasi-careers before this dream becomes a reality, if at all.
2> Coffee Shop Owner. The weird part? I really don't like coffee all that much. I just love the smell, the atmosphere, and the general "at-ease" nature of the place. Imagine a work place where the most stressful object in the entire office is a phone ringing quietly on a counter. If I could afford to do this, it'd be all I would do. I'd work the entire day, open to close, if I had to.