If you’re an exercise newbie, start slow. Interval training is intense and can put a fair bit of strain on the heart — especially for the more sedentary amongst us. If hitting the gym isn’t already a regular part of your week, talk with a personal trainer to design a customized introductory program. If you’re already versed in fitness, start with once or twice weekly interval training sessions, bookended by strength training and low intensity cardio on non-interval days.

The Takeaway: Gradually introduce interval training to your already established routine. Increase the frequency, intensity, or time (FIT) of each new interval training session by 10 percent to get stronger.

Make It Happen Like a Greatist: Next time you hit the treadmill or elliptical, introduce 15 to 20 second sprints, followed by 30 to 45 second breaks.

The Break Down

Your complete guide to interval training.

Can I Do Too Much Cardio?

What happens when the heart doesn’t get a break.