Both of us make each other do it. If you're an avid treadmill jogger, pairing up with a die-hard swimmer may not work out. Still, you could get together for strength training. Obviously, the partner needs to be available when you are. With some flexibility, you can work out a meeting time.
Many people use their lunch hours to team up with a partner.
Set a specific time and date for your meeting. If you leave your workout schedule up in the air, it won't happen. Decide when you'll meet, what you'll do for your workout and how long it will take. The better you plan, the better the results. Make a ground rule that the only excuses for not attending are being sick or injured.