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.