Crank up the Intensity

If you’ve been exercising and your volume is nearing maximum capacity or you’re crunched for time, then add more challenging workouts like speed-work or hills that strengthen your anaerobic system. Running a hill with a five-percent grade burns about three to five additional calories a minute. The key is to do these workouts prudently—no more than once or twice a week—and to pay attention to your form so that you don’t strain a muscle or otherwise get injured. Follow a training plan appropriate for your level of running.