Walking is a wonderful way to stay active and comes with , including less back pain and improved fitness and mental health. But what if the weather is unbearably hot or cold? Or what if you don't have easy access to a walkable area? Is walking indoors just as good for you? While there are many unique health boosts that come from being outside, indoor walking or walking on a treadmill, can still be great exercise, says Stephanie Mansour, certified personal trainer and contributor. Walking or running outside tends to be more challenging than inside, which may be a pro or con depending on your goals and your fitness level.

When you're walking outside, "there's more variation in your speed and your pace," Dr. Jeanne Doperak, a primary care sports medicine physician at the University of Pittsburgh Medical Center, told TODAY.com previously.

You'll also be more likely to encounter different inclines and types of terrain, Mansour adds, like uneven pavement or a rocky, dirt road. "Physically, the different surfaces challenge your balance more than they would if you were on a treadmill or walking in place inside," Mansour explains. That means your workout will engage your leg muscles in a more "randomized" way, Mansour says.

"When you walk uphill, you're using more of your glutes and hamstrings as opposed to walking downhill, when you're using more of your quads," she explains. While you can replicate some of that by adjusting the incline on a treadmill, it's not the same as being chal.