Anytime you are going to hang out with someone you haven't seen for a while - do something active. Take a walk, go bowling - whatever. So often, our social time revolves around food - switch it up!
Also - if you call up a friend and they can't hang out with you, schedule a workout time right then and there with them for the future. Don't say "ok, sometime next week" - pick a date, pick an activity, and chisel it in stone. This will add accountability AND variety to your workouts!