There’s something about taking the stairs that truly messes with your confidence. You can feel like the most in-shape person in the world, totally killing it during HIIT seshes, turning up the RPM on your spin bike like you’re gunning to win the Tour de France. Then the second you start ascending to the front door of your walk-up apartment, you’re suddenly more winded than you’ve ever been. Well, it turns out all those flights are the ultimate fitness test and can say a lot about whether you have solid exercise capacity—or the ability to handle high levels of physicality—breathless or not.

In a new study published by the European Society of Cardiology, 12,615 participants did a treadmill evaluation to test heart strength by measuring metabolic equivalents (METs). One MET is the amount of energy your body uses to sit quietly (walking is matched with 3 METs and jogging 6 METs), Today reports.

And, you guessed it, that’s where the stairs come in: If you can quickly climb four flights in 45 to 55 seconds without stopping, it equals the max of 10 METs, meaning you have great exercise capacity (and deserve a pat on the back). And if you can’t do it? You probably aren’t getting enough exercise.

If you can quickly climb four flights in 45 to 55 seconds without stopping, it equals the max of 10 METs, meaning you have great exercise capacity.

Furthermore, a follow-up test found that for every MET increase participants achieved in the exercise test, the risk of cardiovascular death and death from cancer were each associated with a 9 percent decrease, and their risk of any other cause of death decreased by 4 percent.

And more good news: It doesn’t matter whether you’re left huffing and puffing after mastering the stair-climbing challenge. Different exercises require different strengths, and no matter what physical activity you’re doing, breathlessness is an asset: “When people say, ‘I can’t exercise because I’m short of breath,’ I say, ‘Great, what a wonderful thing, I want you to use that your advantage,'” says cardiologist Andrew Freeman, MD.

So the next time you’re faced with what looks like a stairway all the way up to heaven, take it as a challenge. You might be winded once you reach the top, but when it comes to your health, you’re doing yourself a solid.

These 11 exercises will give you Michelle Obama-level arms, no weights necessary. Or you could try the twofer exercise that works your abs and butt in a single move.