Sweeney is a contributor for TIME. Photo-Illustration by Chloe Dowling for TIME (Source Images: Natalie Board—Getty Images, Ira T. Nicolai—Getty Images, Tess Trunk—Getty Images, fongfong2/Getty Images ...

For someone who is 155 pounds, 30 minutes of vigorous lap swimming can burn 360 calories, per Harvard Health. By comparison, ...