Running on a treadmill can get boring. So when another guy jumps on to the one next to you, it’s no surprise that can liven things up a bit. There’s nothing wrong with embracing your competitive urges, says Joel Fish, Ph.D., a sport psychologist and director of the Center for Sport Psychology in Philadelphia. But if you become too emotionally invested in the outcome of the “race,” that can indicate a problem.

In addition to the risk that you may end each workout feeling second best, you may undermine your fitness gains by ignoring your pace and form, says Fish. So if your run feels rote, don’t look to either side for competition: Set multiple personal goals before you hit the machine to spice things up. That can be things like beating your one-mile time, improving your speed work, or running for 30 minutes straight without stopping. Or you can try these 6 Treadmill Workouts That’ll Kick Your Ass.