We all understand investment when it comes to money: Put $100 in now, and in a decade, you have an exponentially bigger sum. Or, at the least, you save it, and it’s there waiting for you when you need it.

But what if there’s such a thing as fitness investment? What if you could sweat it out now and still see benefits 10 years in the future?

I was stunned to learn that’s exactly what happened in a study conducted in North Carolina. From 1998 to 2003, 161 sedentary adults were assigned to either a control group (no exercise) or one of three exercise groups, which varied in amount and intensity. The study lasted for eight months. Ten years later, 104 of the original participants came in for a reunion study that measured medical history, body size and composition, endurance levels, and metabolic markers like glucose, insulin and lipids.

Shockingly, waist circumference was smaller in people from all three exercise groups (compared with the control group)—even in those who had not stayed physically active. Cardiorespiratory fitness declined 10.5 percent for those in the control and moderate fitness groups, compared with only 4.7 percent for those in the higher-intensity groups.

And here’s the kicker: Those in the low-amount/moderate-intensity exercise group had the best 10-year markers for insulin and blood pressure levels, compared with all the other groups—again, even if they didn’t stay physically active. That means a vigorous walk today may have the biggest influence on your future metabolic markers.

What’s more, those who did stay physically active experienced the smallest losses—and often even gains—in fitness and metabolic markers at the end of the decade.

The researchers admit they don’t know why the exercise benefits seem to linger. But in practical terms, it doesn’t really matter why. If you need motivation to work out today, just think of how thankful the future you will be that you did.