If you are a club player - your not playing for fame or money normally - so what are you playing for?
I play: - to have some fun
- to improve my skill set
- to have social time - to get exercise
If these are your aims too - then why would you ever get mad at yourself, your partner or your opponents?
On the times that this has happened to me - I had lost site of my goals for playing tennis.
Now that I am clearer on what I play for - I am having so much more fun, improving faster, having more pleasant interactions AND I have kept my weight to a healthy level!!!