I can fix most of my rear flats in about 10 minutes. I taught myself out of one of the Zinn maintenance books. Usually the part that takes the longest is finding the cause of the flat. My vision is not so hot, so I usually have to seek out really good light in order to find the gravel/glass/thorn/whatever, although sometimes I haul out my headlight for help.

Every so often I see someone walking a bike with a flat, with a devastated/lost look on his or her face. When I offer to help with the flat, they always act very surprised that it is a repair that can easily be done on the spot, with simple, cheap tools. I'm of the opinion that a big barrier here is ignorance - if you don't know that it can be done, you aren't going to learn.

I tend to get a little excited whenever something goes wrong with my bike, because then I get to learn how to fix it. Last week I got to adjust the headset