New technology, services, and caregiving concepts will be necessary to address the needs of an aging population.

So there’s good news and there’s bad news.

The good news is there are steps you can take to slow your heart’s aging process, increasing the chances of living a long, healthy, fruitful life. The trade-off is that you really do have to go to the gym.

New research published this week in the Journal of Physiology pins down the number of days a week a person should exercise to maintain the overall health of their arteries, which stiffen with age and, as they do, increase the risk of heart disease and heart attack. Very few people experience heart attacks before age 45, and the average age is 65. But the new study suggests a way to keep your arteries physiologically “young.”

The study considered that every human has different-sized arteries, and found that the smaller arteries rely on fewer days of exercise per week than larger ones to maintain overall health. The takeaway: Medium-sized arteries need two to three days a week of 30-minute exercising to minimize artery stiffening. But to minimize the stiffening of equally important larger arteries, people should be exercising four to five days a week.

“This work is really exciting because it enables us to develop exercise programs to keep the heart youthful and even turn back time on older hearts and blood vessels,” one of the researchers said in a statement.

It might not be easy, carving out more time for exercise, but at least it’s more clear what you can to do achieve better heart health over a long period of time. That’s especially positive news for people in the US, where heart disease remains particularly deadly, thanks in part to the nation’s obesity epidemic. More than 610,000 people die of heart disease in the US each year—accounting for about 25% of total deaths, according to the US Centers for Disease Control and Prevention. Each year more than 735,000 Americans have a heart attack and 28% of those are a second heart attack.

The scientists came to their findings by examining a group of 102 people—all of them older than 60—who had exercised over the course of their lives. The researchers started by measuring each person’s artery stiffness, then grouped them into four categories depending on how much they exercised through the years. One group was for people who generally exercised less that twice a week. Another was for “casual exercisers” who were active two to three times a week. The last two groups were for people who exercised four to five times and six to seven times per week.

“A lifelong history of ‘casual exercise’ resulted in more youthful middle-sized arteries, which supply oxygenated blood to the head and neck,” the press release states. “However, people who exercised 4-5 times per week also had more youthful large central arteries, which provide blood to the chest and abdomen, in addition to healthier middle sized ones.”

This work showed exercise training over a long period of time can slow artery damage and the aging of the heart; the researchers say the next step is to study whether it can also reverse damage and aging of the cardiovascular system.