Push it

Keep Challenging Your Body
It may have been just a few weeks ago that you were an exercise newbie. Those first workouts were rough — you didn't think you'd ever survive! But now look at you — you're working out on a regular basis and improving your diet. Good for you!
Know what? It's time to bring the hammer down again. How do I know? Because your body is getting just a little too accustomed to the workload that originally taxed it to the max. Remember — to see continual results, you have to keep challenging your body.
Once you've been exercising for several weeks, it's safe to increase your intensity, and I recommend working out at about 85 percent of your maximum heart rate. To monitor your intensity, first calculate your maximum heart rate by subtracting your age from 220 if you're a woman, or 226 if you're a man.
Once you've calculated your 85 percent rate, you can keep yourself at the right intensity by taking your own pulse throughout your workout. The quickest way is to count the beats for 6 seconds and then multiply by 10. You should check your pulse every 10 minutes or so.
Sometimes during weight training your heart rate will jump above that 85 percent mark, which is fine. If you're using weights, just make sure that your heart rate doesn't drop below 75 percent of your max for the duration of the workout.

Use Your Judgment
Don't have a heart rate monitor, or have trouble finding your pulse? No worries — when it comes to intensity, you'll learn to use your judgment. If your workout feels too easy, increase the intensity; if it feels too difficult or your form is compromised, decrease the intensity. You will find that your ability level changes as you keep working out and getting stronger, so it's important to understand your body and know when and how to increase your efforts in order to keep moving toward your goals.