A bad blister can stop a good workout cold. Here's how to keep blisters at bay, according to dermatologist Michael L. Ramsey, M.D., of Penn State Geisinger Medical Center in Danville, Pennsylvania.

Buy shoes specific to your sport (e.g., walking shoes if you're a walker, running shoes if you're a runner).

Allow a thumb's width of space between your longest toe and the end of the shoe.

Try on shoes in the afternoon or evening (because your feet tend to swell a bit during the day); wear the same socks or orthotic inserts you use during exercise.

Minimize the friction that causes blisters with a thin layer of petroleum jelly on areas particularly prone to them.

Keep your feet drier (moisture also helps promote blister growth) with a foot powder or foot antiperspirant.