Getting sweaty is good for you, but sporting damp, clammy clothes is not — it creates a breeding ground for fungus and can cause chaffing. This quick-dry Nike base layer nixes such problems. The back panel is more than 50 percent mesh for plenty of airflow and evaporation. Ideal for any temperature-ratcheting activities where you might want to shed some clothing — like running, biking or yoga in a hot studio. $35 at www.nike.com.