The North Face GTD Crew - Short-Sleeve - Women's - $39.95

Sure, you could run in a cotton T-shirt, but you don't feel like soaking in your own sweat and then getting the chills. The North Face Women's GTD Crew uses high-tech FlashDry to quickly move sweat away from your skin and accelerate evaporation for enduring cool, dry comfort. It also features smartly placed ventilation panels for added airflow where it's needed most. All this and in a soft, lightweight package that always feels good. - $39.95