Define Winning

I would define winning as achieving your performance goals, for instance: serve and volley every first serve in doubles, return all second serves and rush the net, hit down the middle and less down the alley, mix in more angle returns of serve, etc. If you focus on the doing and less on the outcomes things have a way of working out better. Play each shot as it's own challenge and enjoy it.

Winning and losing are just outcomes. Enjoy the process of tennis.