“Another great aerobic workout, swimming is low-impact and amazing for staying in shape,” Dr. Gioffre says. It also works wonders on your lungs. “Your body learns to use oxygen more efficiently, to breathe in more fresh air and breathe out more carbon dioxide.” And deep breathing is one of the best ways to fight acid. Many people find swimming to be a big-time stress reliever too, so you’re fighting acid on multiple fronts, he adds.