The treadmill: It’s a godsend for serious runners who want to get their workout in even when the weather is bad. There’s no wind resistance, you can adjust the grade of your “terrain,” ease the impact on your joints–or in some gyms, even watch TV!

But of course, there is such a thing as too much of a good thing. Running exclusively on a treadmill–or any other type of terrain, for that matter–can prevent you from achieving the well-rounded workout regimen you’re striving for. Eric Blake, head cross country and track and field coach at Central Connecticut State University, says, “Changing running surfaces works different leg muscles, which will lead to physical benefits…And different scenery in your running will lead to mental benefits.”

Indeed, fitness buffs are known for being creatures of habit–but by breaking these habits every now and then, you can establish a routine that reduces cumulative stress on individual muscles and joints.

On the Road

While streets and roads can offer consistent, flat surfaces, they’re not great for your body. If roads are your primary running surface, seek out softer terrain at least once a week, such as a trail or an athletic field. Running on softer surfaces will help minimize any chronic discomfort, develop your ankle and lower leg strength, and improve your recovery time.

On the Grass

Soft and low-impact, grass is a great surface for runners who might have a history of joint impact issues such as plantar fasciitis, stress fractures, or anterior knee pain.

However, running on grass–or dirt, for that matter–can be unexpectedly hazardous, according to physiologists at the University of Texas. Grass runners must be extremely aware of their surroundings, especially if running at a park. Look out for terrain abnormalities like ditches, holes, and other obstructions; and be aware of any pedestrians, strollers, and dogs that might cross your path.

On a Treadmill

As mentioned earlier, treadmills can be a great way to get your exercise in when it’s particularly wet, cold, hot, or windy outside. Also relatively low-impact, they can be great for athletes who are still recovering from injuries or out of shape, as the belt does help “pull” you along a bit.

However, to make the most of your treadmill runs, be sure to vary the incline throughout your session so you’re training more muscles. And if you’re preparing for a marathon or another competitive race, don’t rely exclusively on the treadmill–you’ll need to be prepared for irregularities on the road!

On the Track

Most modern tracks today have a “spongy” surface that strikes an ideal balance between firm and soft. However, if you have pain in your calf muscles or iliotibial band syndrome, you might want to avoid tracks, as the constant circling can put undue stress on your shins and ankles. If you must run on a track, to be safe, try easing up as you round corners.

Diversifying your running surfaces can be a great way to prevent muscle burnout and stave off running-related pain. If you experience chronic pain from running, talk to your physician or physical therapist.