After you've been running for at least six weeks, add intervals to continue building fitness and shedding pounds. Intervals are short bursts of speed that engage the muscle fibers that make you go fast. (Bonus: Research has shown that sprints trigger a fat-frying response in your muscles.) To do them, warm up for six minutes with an easy jog. Then run faster for 15 to 20 seconds. Slow down to an easy pace for three minutes. Repeat the cycle three to five times, then cool down with a six-minute jog. Do intervals once a week and increase your sprint length by 10 seconds each week until you can go all-out for 80 seconds.
More: 27 Ways to Run Better Everyday
Keep It Up!
Nothing bursts your bubble faster than an injury. Take a few simple precautions and you'll rarely—if ever—be sidelined.
Increase your runs gradually. Up your running time by no more than 10 percent a week, Holland says. That means if you run a total of 10 miles one week, aim for 11 the next.
More: Exercises to Increase Your Running Speed
Shore up the rest of your body. Weak muscles are prime targets for injury. Strengthen them with a biweekly 20-minute strength-training session that targets all your major muscle groups, Holland says. Try the total-body plan at womenshealthmag.com/fitness/total-body-workout-8.
Stay flexible. "Running makes muscles short and tight, which can compromise your form and cause injury," Holland says. Stretch after a warmup, then repeat after your run (stretching when your muscles are cold can lead to injury). Find great stretches at womenshealthmag.com/fitness/stretches.
More: 6 Yoga Poses for Runners
Stuck Inside On A Treadmill?
Set it to a 1 percent incline to get the same caliber workout as running outside.
Source: Journal of Sports Science
Burn More Fat!
More: 7 Ways to Eat Smart and Lose Weight
Supercharge your workout with these Web-exclusive tips only from womenshealthmag.com.
Sign up for your next race.