If you're just starting out, Alex Harrison, PhD, CSCS, who's also a level three USA Track and Field coach, recommends running twice a week, gradually building up to four times a week over the course of five weeks to avoid injury.
ACE-certified personal trainer Rachel MacPherson said to begin with 20- to 30-minute runs at a comfortable pace every other day. As you're ready, Jeff Godin, CSCS, head of fitness education at Spartan Race, Inc., said to aim for 45- to 60-minute sessions; you don't have to run straight for the entire workout. "Break the run up into small digestible pieces," Godin said. Run for one minute, walk for two, and gradually build up.
ACE-certified trainer Amanda Brooks added that "20 to 30 miles per week is plenty for someone looking to lose weight and improve overall health." Remember that doesn't need to be all from running. All those extra steps add up, so make sure to include daily walks, aiming for at least 10,000 steps a day.