Runner's high

I was talking with some fellow-exercisers recently and the subject of runner's high came up--those natural endorphins from exercise. Everybody else at the table said they got it. I never do. I don't think I ever have, even in high school when I'd bike 20 miles without sitting down. (Whatever my other faults, I had a pretty good ass back then.) One of the guys I was talking to was puzzled and said, so you just power through your workout?

I guess I do. I exercise at 5:30 AM. Now that I think about it, that's pretty much the low-energy point of my day. I like the sensation of muscle fatigue I get later in the day, but it doesn't feel good while I'm exercising. Another guy I work with loves to eat pizza for lunch because the carbs let him go home after work and lift harder.

What's up with that? Should I be doing something differently to get that high?