A playful cardio joke landed on a real health point: daily heart-rate-raising activity is good for you, though the exact 15–20 minute rule isn't set in stone.

Other research shows that regular physical activity helps people live longer and healthier, but that study didn't specifically test whether 15–20 minutes of heart-pumping exercise is the key. Another piece of other research found that getting your heart rate up can help blood sugar, but it didn't prove you need exactly 15–20 minutes every day—shorter workouts helped too. A more direct piece of other research found that daily activity raising your heart rate, especially at moderate or vigorous intensity, lowers the risk of heart problems and death, even in short bouts. So 15–20 minutes a day fits comfortably with what the evidence says is good for you. The caveat is that the exact duration isn't something the research has pinned down as a strict daily requirement.