Here’s something that will make you feel better about skipping the gym (again): too much exercise is worse for your heart than not being active enough.

There’s no denying that fitness is beneficial, but it’s still unclear when that time on the treadmill becomes too much of a good thing. Researchers at the University of Illinois at Chicago delved into the link between physical activity and artery health, particularly fat build up. Medically known as atherosclerosis, the condition is a precursor to more serious problems including heart attacks. And as the authors note, few long-term studies have looked at activity levels throughout our lifetimes, and the subsequent effects.

The team studied 3,175 men and women over the course of 25 years. Participants were divided into three groups: those who exercised less; those who met the U.S. Department of Health’s recommended guidelines for physical activity; and those who exceeded those guidelines. The current advised standard is at least 2 hours and 30 minutes a week of moderate exercise or 1 hour and 15 minutes of strenuous aerobic workouts for adults.

All the participants were from the larger Coronary Artery Risk Development in Young Adults (CARDIA) study. They reported exercise levels using questionnaires and participated in eight exams throughout the study. At the end of the investigation, researchers used heart scans to determine artery health.

After 25 years, the data revealed that white men who exceeded three times the recommended guidelines were at an increased risk of accumulating fat on their arteries by the time middle age set in. The same did not seem to be true for black adults participating in the survey, causing the researchers to note the importance of further studies examining how physical activity impacts heart health by race.

But it’s not time to store those gym shoes just yet. The data also found that people who didn’t exercise enough were more likely to have type 2 diabetes and high blood pressure. So although they may have had less fat on their arteries, they did suffer from two conditions that are bad for your heart.

It seems that with almost everything in life, the key is in balance. Cardiologist Dr. Joel Kahn told CBS News that mixing up your workout routine can help avoid some of the pressure that exercise puts on your body. “There is a stress reaction to long distance and long duration exercise—your cortisol is up for a long time,” says Khan. “It may be wise to build in daily stress reduction techniques, such as meditation, yoga—seven, eight hours of sleep.”

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