Do you always make sure you do at least a full hour of cardio followed by weight training when you work out? Do you feel like you are being short-changed if a class is less than sixty minutes? Are you always looking at the clock so you do not do less than an hour of exercise? If you answered yes to any (or all) of these questions, you need to rethink your workout. When it comes to exercise, it is what you do that counts—not how long you do it.

I often see women take a class and then immediately hop on a treadmill or stair climber for an additional ten, fifteen or twenty minutes of cardiovascular exercise. Sometimes they do a pre-class workout for a period of time. All this does is lead to burning out rather than burning extra calories. The truth is that you should be pretty spent after a workout—so much so that the thought of doing anything more feels almost impossible.

There is no rule that you must exercise for at least an hour. An effective workout should be big on intensity and effort, not on time. If you look at most CrossFit workouts, for example, some of them are twenty minutes while others are significantly less. Their philosophy is to push you as hard as they physically can and then have you go even harder. At that kind of intensity, there is no need to go longer nor is there any energy left to do so. When I attended a CrossFit demo, my heart rate was through the roof, my calorie burn was over two hundred, I had no energy left to do anything else—and I only worked for ten minutes!

While CrossFit is not for everyone, another great workout that emphasizes quality over quantity is circuit training that incorporates both strength and cardiovascular exercises. Choose exercises that work all the major muscles and push through each one for either a certain amount of reps or for a set amount of time (usually thirty to sixty seconds) with no rest in between them. When you complete all the exercises in the circuit, rest a minute or two and go through it again two more times. The goal is to keep moving throughout the entire circuit with minimal to no rest. This will get your heart rate high and keep it high even during the strength training moves. The other key element is to use weights that are challenging. If you get through your reps easily or your heart rate is not increasing much, use heavier weights on your next round.

The most important thing to remember is not to plan your routine around a specified amount of time. One of the problems when you work to the clock rather than the intensity is that your workout suffers. You figure you can take your time working up to a good sweat since you have an hour to do so. Sure, you want your body to warm up, but that takes five to ten minutes. After that, you should be going all out so that an hour is not necessary. The same goes for strength training. You do not have to use every machine in the gym or do every possible exercise. Choose the ones that work multiple muscles at once like push-ups, pull-ups, squats and lunges. These are highly effective at not only making you stronger, but they will also get your heart pumping which means no need for an additional hour of running, rowing or biking.

I have done some of my toughest workouts in a thirty to forty-five-minute period. There was no need to tack on additional minutes just because it took less than an hour. Frankly, I couldn’t even if I tried. And that is how you should feel after a workout. The last thing you want to do is over train which ultimately has a negative effect on your body and your health. It can also lead to overuse injuries and decrease your immunity which can completely derail your workouts altogether.

Do not let time be your gauge when it comes to exercise. If you hit the ground running, you will realize that there is no need to run that extra mile, climb that extra set of stairs or row another one thousand meters. Why spend all that time in the gym spinning your wheels or climbing endless stairs? Enjoy having some extra time—something that does not come along often when you are a busy mom. Remember, the goal is to burn calories—not burn out.