My favorite workouts are multi-hour walks around the city—especially since we've been cooped up. Bitterly cold winter temperatures can make my excursions miserable, so I asked for these thermal bottoms for Christmas. They perfectly balance warmth and breathability, and are light enough to wear under my leggings—that way I can simply transform my existing collection into winter-ready gear rather than buy new fleece-lined sets. And even if I do sweat (sometimes those walks are strenuous!), these thermals are built with Pategonia's HeiQ Fresh, which blocks odor-causing microbes. Now my bottom half is toasty warm, I won't have any excuse not to keep up my walks.