While it's important to give your body downtime, you don't have to plop down on the couch all day. Light cardio helps get the heart rate up and blood flowing, which will bring oxygen and nutrients to sore muscles. So unless you're injured or have strained a muscle, get up and move a little! Use this day to stroll through your farmers market, take a walk with a friend, or go on a leisurely swim. Also, switch up your workout — if your legs are sore, work on your upper body, or vice versa.