Ask YC: When did you start having interesting ideas?

The other day I was trying to recall examples of specific interesting ideas I'd had before I started keeping an idea journal, which was around the time I went started college. The funny thing is that I really couldn't come up with much of anything. There was an essay that I'd posted on my homepage about an insight I'd had my freshman year of high school, but that was the earliest specific example of a non-trivial idea I could remember having. So I am still trying to figure out whether I just didn't start having interesting ideas before a certain point, or whether I did have interesting ideas but have just forgotten them all because I didn't write them down. I'm leaning toward never having had interesting ideas in the first place, but it's difficult to say. There seems to be a lot of cognitive research on ability to remember specific tangible events and routines from childhood, but not so much on ability to remember one's early ideas.

So how do I define an interesting idea? As a working definition, I'd say a prerequisite is that it's something novel. Maybe not totally unique, but at the least the kind of idea where you say, wow, I bet maybe maybe a few dozen or a couple hundred people have had this same sequence of thoughts before.

Examples: Seth Godin had an interesting idea the other day that as the price of gas increased and telecommuting became more common, the expectations for the quality of in-person interactions is going to increase accordingly. Nothing super complicated, just a simple cause and effect, but still I think it meets the minimum level for being novel and interesting. Seth comes up with a lot of novel ideas. Edge.org is filled with them.

I don't want to give any definition that's too precise though because I don't want my preconceptions to bias others. Other people obviously spend their time thinking about different stuff than me, so the set of things that qualify is probably larger than anything I'll be able to clearly articulate.

So when did you start having interesting ideas? What was the first non-trivial idea you ever remember having?