It shouldn’t come as a surprise to anyone that if you want to lose weight, you have to put in the work. For years magazines, reality television shows, and medical studies have told us cardio is most important if you’re looking for fast results. All too common though, is the runner who hits a plateau and can’t seem to lose those last 5 or 10 pounds. So what’s the deal?

Many people figure the longer they workout, the more weight they will lose. This claim will sometimes hold true, but for the most part it does not matter how much cardio you’re getting, but rather at what intensity level you are performing.

Take a look at this scenario: Bridget walks into the gym every weekday morning at 6 a.m. She puts her headphones in her ears, flips the channel to The Morning Blend, and starts peddling away at the elliptical. She stays on the machine for 45 minutes, fits in 15 minutes of abs, and does the same thing the next day. If Livestrong.com recommends 30 to 45 minutes of cardio three days a week, then this would mean Bridget should be in top shape. But Bridget’s been the same weight for years, and has yet to achieve that flat stomach she’s been working for.

Bridget’s workout routine is popular among many girls on campus. Their goal is to be lean with washboard abs– which is not a bad goal. However, this routine does not work because it doesn’t challenge the body enough. Just like a cold virus, your body essentially becomes immune to workouts. By doing the same exercises every day, you’re heart rate is not reaching the proper levels to burn fat.

If you want to see results make sure you break a real sweat. By that I mean, don’t hold back at the gym. Don’t be afraid to push yourself to your absolute max. Switch up your regular routine by adding weights, trying different classes, trading in your 20-minute jog for a timed mile, or participating in a recreational sport. Sure you may be a little embarrassed at first (it’s not every day you see someone timing their sprints on a treadmill), but trust me, in time you will be happy with the results.