Red flag: sore, tender soles

Flat-soled footwear seems like a sensible bet, but many styles—including ballet flats, UGGs and snow boots—lack arch support. “Without arch support, the plantar fascia,a band of tissue that runs beneath the foot and connects the heel to the toes, is subject to undue strain with every step,” says Dr. Brenner. This can lead to plantar fasciitis, a condition marked by sharp pain in the heel and arch of the foot that typically occurs first thing in the morning, as well as after prolonged sitting and when climbing stairs.

FOR FAST RELIEF: If your soles feel even a little sore, Dr. Brenner recommends freezing a bottle of water and rolling it under your arches for one minute, pausing for a minute and repeating for 10 to 20 minutes total one to three times a day. “It’s a favorite among my patients since the combination of ice and massage eases inflammation and tightness.”

FOR LONG-TERM HEALTH: To prevent pain from progressing into full-blown fasciitis, Dr. Brenner advises outfitting your flats with insoles that add arch support and shock absorption (like Powerstep Pinnacle Shoe Insole Orthotics, starting at $19, Amazon.com).