By mid-winter, you’ve probably sweated it out on the treadmill to hours of bad TV and burned through your music playlist more than a few times.

With all that work, you think you’d be hitting your stride and ready to set a personal best in your next race. But for many of us, all of that effort on the treadmill often doesn’t leave us faster or leaner—often because we’re forgetting to change up our routines.

“If someone isn’t seeing desired fitness results or progress in their speed while running inside, outside or a mixture of the two, it’s a lack of variation in their workouts,” says Amanda Verrengia, a Pittsburgh-based personal trainer and running coach who operates Run Intended, her own coaching business.

“It’s important not to allow your body to get used to the demands you’re putting on it.”

When running in place on a treadmill, runners should try to mimic the changes in landscape that we typically encounter outdoors, Verrengia says. You can do that by changing up the incline level. Remember it’s just as crucial to change up your pace while you charge up and down on different incline settings.

Another benefit of the treadmill is that, unlike running outdoors, the

treadmill can keep you running at a faster pace because you set the speed. This can be good for improving speed.

“It can help you to push the pace, because when you set the miles per hour, you’re forced to keep up,” Verrengia says.

“If you’re a treadmill lover or you’re forced indoors all winter due to weather, definitely set a weekly plan that includes some speed play, easy miles and tempo.”

As the miles tick away, don’t forget to think about your form. Verrengia says runners often shorten their stride on a treadmill, in part because the lack of space can make them nervous.

“On the treadmill, sometimes the arm swing isn’t as efficient,” she says. “Be sure to continue to use the arms as you would outdoors, with a quick and strong drive.”

And while time on the treadmill can certainly boost fitness and speed, Verrengia says runners who want to see results or are training for a race should try their best to get outside at least a couple times per week when possible to prepare themselves for different types of terrain and weather.

“Even on the best treadmills you won’t be able to mimic the weather and the wind speed, which can affect your ability to propel forward,” she says. “It’s important to transition to outdoor running as the race nears.”