Prescription for Danger: 7 Harmful Shortcuts

You sprint straight into the shower after your Spinning class.

We know: You have to get back to the office. But slamming on the brakes after a hard-and-fast workout is bad for your bod. "When you abruptly end a cardio session, your heart rate plummets and blood pools in your large leg muscles, which can make you feel light-headed," says exercise physiologist Kara Mohr, PhD. It takes about three minutes after you stop exercising for your need for this additional blood to lessen, so cool down for at least that long -- preferably a few minutes more -- to allow your blood flow and body temperature to return to normal. "Any movement that lowers your heart rate and decreases the intensity of exercise, including walking, slow bike pedaling, and standing lunges, is good," Mohr says.