I try to ride every other day, regardless of the heat. If I didn't, I'd weight 300. I always wear a helmet. Here in Arizona, most morocycle riders don't wear helmets. I always think they look stoopid when they go by with their faces distorted by the wind, tears streaming out of their poorly protected eyes...
I had a front flat rewcently going maybe 5 miles an hour, the bike went completely out from under me. I had no chance to un-clip, and landed head and shoulder on the concrete. I laid there maybe a full minute, mentally checking for injuries. Made it out with only a good sized headache and badly damaged pride. The accident was witnessed by my wife and two small girls on their bikes, all of whom rushed to my aid!
Another time, mountain biking, I tried a pretty steep incline and went over backwards. Helmet and Camelback protected me from major injuries!
Steve, I am truly sorry about your mishap. We would all be worse off without you!
If biking didn't have its dangers, it wouldn't be as fun. The goal is to minimize the risk, and go for it!