It's not easy to stay fit in the cold of winter, but a few tricks can help. Start by upgrading your tracksuit. These days, technical fabrics, such as neoprene, helps a runner stay slick and warm thanks to its insulated, "scuba" texture. West Coast brand Everlane has a refined take on this modern classic: a fleece hoodie, with a zip that fastens all the way up to the chin. Adding function to form, there's also matching sweatpants, and the whole look is available in heather gray (pictured) or navy blue. Ready. Set. Go!