18 is by no means too old to start boxing competitively. However, you're not likely to be a world champion.

I started when I was 16. A guy from my high school football team brought me to the gym with him after watching me beat up a 30 year old man in a Denny's parking lot. He figured that at 6'3" and 215 pounds of muscle, I was something of freak as a 16 year old.

I first fought as an amatuer a couple months after I first went to the gym. My career ended a few years later with a broken hand when was 26-1. Couldn't fight that often playing football and basketball.

Even starting at 16, I was able to be a pretty good amatuer. In fact, I thought I was damn good until...

A couple years before the '04 olympics, I was able to spar with Jason Estrada. He was the US SHW in '04 in Athens. I think he's since turned pro, so you could probably find him on boxrec. By that time I was up to about 225 pounds. I was taller, faster and stronger than Estrada, (who's really not much of what Larry Merchant would call a specimen). Didn't do me a damn bit of good. His skill level was soooooo far beyond anything I had seen as an amatuer in Chicago. He dropped me. I was able to continue. But the more I tried to bully him, the worse it got for me.

That's the difference in skill level between someone who started when they were 16, and someone who started as soon as they could walk.