Confession: I once used a dating site to find tennis partners. I trolled OkCupid and searched for profiles that included the words tennis or Federer or Djokovic, and then I messaged women to see if they wanted to play. They didn’t. Apparently, “Hi, I’m not really looking to date, but I’d love to improve my backhand,” is not the way to anyone’s heart.

Evidently science has proven my desperation to find a partner as multiple studies have shown the benefits of one: Having someone to exercise with makes you more likely to hit the gym more frequently and accomplish your goals; you’ll push yourself harder than if going solo; and it improves mood.

Having a workout buddy can also boost your performance. One study of the Oxford University Boat Club rowing team showed that the group who rowed in unison released more endorphins and rowed harder and faster compared with rowers practicing alone. And the extra influx of endorphins into their brains resulted in a higher pain threshold, allowing them to row longer and hurt less.

So if you’re in the market for someone to pound the pavement or bang the plates with—or lob tennis balls back and forth to—here are a few traits to look for. 

1. Accountability

No more snoozing when someone’s relying on you, otherwise guilt kicks in. Roll out of bed and take care of business.

2. Availability

Same gym, same hours, same geographic location. Long-distance workout buddies work about as well as long-distance relationships.

3. Positivity

The words emotional support might sound like something from an old Oprah, but one study from Aberdeen found that “emotional social support” from a workout partner increased workout frequency.

4. A (slightly) higher skill level

Ideally, your partner is just a bit better than you are at the activity, but not so much that there’s a glaring discrepancy. A study from Kansas State University found that the “optimal exercise partner is 40% better than the other, motivating the less-skilled partner to exercise for a longer period of time and at an increased rate.”

5. Platonic only

Rule of thumb: You should not want to have sex with your workout buddy.