Beginnings of a bald spot appeared at 21. I kept a normal hair style until about 30, though it was getting noticeably thinner on top. Since my mid-30s, I crop it down to stubble with clippers, or just shave my head.
I used to stress over it a little, but it's honestly not a big deal. Just be a confident and positive person that others enjoy being around. Nobody will care about your hair. Sure, a full head of hair would be nice, but so would being 3 inches taller or a minute faster at 5K. It sure beats having an injury end your running career, or having a chronic illness, or other trouble your body might throw at you.
Do other bald runners wear hats during long runs and races? This is the only place where I think baldness is really working against me. Even if I don't sunburn, I feel like an hour or more in the direct sun on my head just drains all my energy. But I also hate hats, and even the lightest weight hat seems to trap too much heat. Some of the top marathoners like Meb are bald, and I don't remember ever seeing him in a hat. My skin is much paler than his, though. How do other balding runners approach the hat issue?