Workouts are typically created to target certain muscle groups. There are butt-sculpting workouts, upper body exercises, chest exercises—you get the gist. But a cardiologist has a friendly reminder for us all: The most important muscle in your body isn’t your biceps or your core—it’s your heart.

“Without your heart, there’s nothing else,” says Andrew Freeman, MD, cardiologist with Jewish National Health. So just how does a cardiologist recommend working your heart for cardiovascular health? “The best way to work out is at least 30 minutes a day of breathlessness,” he says. (If you have a medical condition, he advises talking to your doctor first to make sure this is safe.) It doesn’t even matter what type of exercise you’re doing, as long as you’re reaching that level.

To make sure you’re truly breathless when you’re exercising, Dr. Freeman advises using what he calls a breath test. “If you can sing or have a full-on conversation with the person next to you, you’re not working hard enough to improve your heart health,” he says. Of course, this doesn’t mean that low-level or moderate exercise is useless—but if you’re really looking to boost your cardiovascular health, he recommends 30 minutes a day on average of being out of breath.

“If you can have a full-on conversation with the person next to you, you’re not working hard enough to improve your heart health.” —Andrew Freeman, MD

When you stop and think about it, though, 30 minutes nonstop of being breathless isn’t easy. “If you’re running really hard for one minute and then you stop, the clock stops too,” says Dr. Freeman. “So it may take someone 90 minutes perhaps to get that 30 minutes of breathlessness in. But as time goes on, the breaks get shorter and shorter so that you can soon get to that level in one go.”

Ideally, you should be doing this every single day, but it really depends on your goals. “The American Heart Association (AHA) recommends 150 minutes of exercise per week, so you can do more or less, but it’s up to you,” he says. Something to keep in mind is that getting in a cardiologist-approved workout schedule isn’t an isolated solution. “Ultimate heart health doesn’t just come from working out,” says Dr. Freeman. The other four heart-strengthening factors, according to him: a low-fat, plant-based, unprocessed diet; low stress levels; love, human connection, and support (yes, really); and proper sleep.

Here’s a 15-minute HIIT treadmill workout to help get you started:

BTW, here are some heart disease facts that you should know about. And these are heart-healthy eating tips you can follow.