Courtesy of GORP, Ten Steps to Happy Feet. Here’s one you learn only after you’ve put some 12-milers in:

Manage Your Toenails:

Socks will catch on nails that are too long or that have rough edges, putting pressure on the nail bed. Nails that are too long are also prone to pressure from a toe box that is too short or too low.

My pinkie toes do this to me constantly: little points grow that dig into the toe next door and leave brutal blisters. It’s amazing how no matter how slowly a toenail grows, it will always reach the annoyance level five miles into a hike rather than, say, on a trip to the bathroom.