3. You read on the treadmill.
“If flipping through a magazine keeps you motivated, by all means do it,” Coopersmith says. “But reading while exercising is so distracting that you’re probably working at an intensity too low to burn a significant number of calories.” Instead, turn on some tunes to increase the duration and intensity of your cardio workout. Researchers at Brunel University in London discovered that runners who listened to motivational rock or pop music (think Queen or Madonna) exercised up to 15% longer—and felt better doing it. You don’t have to nix TV shows, cell phones, books, and magazines every workout—just leave them behind a couple of times a week so you can focus on intensity.