If you’re struggling to squeeze three or four runs per week into your schedule, you shouldn’t worry about adding in other aerobic activities. But once you have a steady running habit, workouts like swimming, cycling, or rowing can boost your fitness without the impact stress of running. And by engaging different muscle groups, you can correct muscle imbalances and net a stronger, more well-rounded body. “This can increase your longevity as a runner,” Mayer says. If you do get hurt, you’ll also have a familiar option for maintaining fitness.

Make It Routine

Stay consistent. Sticking to a regular class at the gym is an easy way to automate cross-training. Even if you go solo, set up a regular date and location, such as cycling in your neighborhood on Monday mornings—context cues help habits to form.

Be realistic. Don’t set yourself up for failure by choosing a class you’ll have to rush to attend. Search for an option that meshes with your schedule.

Choose wisely. Gunning for a PR? Go with a type of cross-training that mimics running, such as cross-country skiing or pool running. If, however, your goal is overall fitness, select an activity that’s very different, like swimming or cycling, Mayer says.

Keep it easy. Treat cross-training like an aerobic recovery day; schedule it after hard running days and keep your effort level low enough to carry on a conversation, Mayer says. (However, if you’re injured and can’t run, you can cross-train harder.) And keep in mind that boot camp or fitnessclasses that involve treadmill running or road sprints don’t count as cross-training—that’s a running workout.