We often hear how we should be doing more—hitting the gym more often, extending that run from 5K to 10K, adding five more reps to that set. But is there always value to doing more, or can you get excess exercise?

The latest fitness study to be making headlines says too much exercise can actually be bad for your heart. The new study, published in Mayo Clinic Proceedings, looked at about 2,400 active heart attack survivors to evaluate the risks and benefits of exercise. (Exercise is commonly recommended for both the prevention of and rehabilitation from heart disease.)

The American researchers found great benefits for most patients who ran or walked: There was about a 65 percent reduction in heart-related deaths among those who ran less than 30 miles a week or walked less than 46 miles a week. But for those who ran or walked more that that, the exercise became a factor putting them at an increased risk of having future heart problems. Competitive runners seemed to be at a particularly high risk.

Though researchers warn that more studies need to be done in order to extrapolate to the general population the point at which exercise goes from being beneficial to harmful (since their study just focused on heart attack survivors), it’s reason to believe that, despite what we’re often told, more exercise is not always better.

Does this mean that you should quit pushing yourself to work harder? In short, no. The vast majority of us aren’t getting enough exercise to begin with, and should be more worried about spending too much time in front of a screen as opposed to too much time working up a sweat. The study authors estimate that about one in every 20 people might be getting too much exercise, while something like 10 out of every 20 are not even reaching the minimum guidelines of about 30 minutes of moderate exercise a day.

And if you are one of those fitness fanatics who loves challenging your body to accomplish new things or traverse new distances? You don’t have to totally take it easy. You just need to find new ways to test your limits without going overboard on exercise. Experts agree that it’s a good idea to switch up your workout in order to work different muscle groups and surprise your body in new ways, so just do something a little different. Move your run to a hilly area, or switch it up for a bike ride.