Sometimes in a tennis match, you can "get down" on yourself or think negative thoughts. Here is a good way to handle negative thoughts.
Think that you have a little bird resting on your shoulder. He is there to help you relax and support you. Refer to yourselves as "Let's" or "We." "Let's" or "We" need to keep the ball in play, keep your eye on the ball, control your breathing or cut down on unforced errors. It will feel like you have your own personal coach on your shoulder. He is only there to help you. Every now and then give yourself a little pat on your back or shoulder. This will become a very positive habit.
If you try this, at least it will take away from spending your time thinking negative thoughts or feeling isolated or alone.
Hope you give it a try. Remember, "Let's" or "We."
Good luck on the Courts!