I spent my last triathlon worried about potentially getting a flat tire (and passed by a woman who had a flat; I felt so bad for her)...so I've been meaning to do something about my complete and utter helplessness in this area. I took a "fixing a flat tire" class at my local bike shop. (This is a skill not just for triathletes: it comes in handy whenever you're biking. I have to say that pulling out all the tools—which you store under your seat in a bike bag—and mastering a flat will make everyone super impressed too!)
If you need a lesson on how to fix a flat tire, check out this step-by-step video (also posted below) from professional mountain bike racer Kelli Emmett.
And if you have no interest in fixing a flat tire, try this fall to pick something you know nothing about (ballroom dancing, mastering a cooking technique, or just a new class at the gym)...and try it! You won't regret you did (and that's my new motto in life: no regrets!)