18 Great Cardio Workouts That Don't Require Running

The next time you find yourself at the ocean, head to the nearest net. "Moving around quickly on sand takes a lot more energy than moving fast on something hard like cement," says Scott Herman, a trainer with the BeFit Network. "The sand shifts under your feet, which means you're constantly correcting yourself and having to generate a ton of power, especially when jumping high." The unstable sand is also great for strengthening legs and ankles, which tend to weaken as you get older. Plus, unlike a grueling 45 minutes of running on a treadmill, volleyball is usually done with friends, so you can go for hours without noticing it.