I play because it's a fun way to stay in shape and also scratch the improvement and competitiveness itch.
So fun is the first priority, but it can become not fun, if we are smashing opponents 6-0, or you see partner not taking it seriously enough, not allowing for long points. Like trying risky shots and failing again and again. Or if you play with a partner that critizes your every shot.
So it's a balance, a matter of finding people your level, so it's fun to play with and against.