Should you want to improve your capacity, you should keep a diary for some time about your practice sessions and your matches. You can then follow exactly the curve of your achievements, your development. Note daily all success, your experiences and your mood. The diary will help you to stay motivated through hard times and help you to get out of a bad mood. It shows clearly you already achieved increase of performance and you will learn that success consists all of small steps into the right direction.
By keeping a diary of success you will help you to keep up a positive attitude and even better it. The psychological effect will show after a couple of weeks. Decisive is the consciousness and the capability to enjoy every reached step on your way to success and to celebrate all. Guard yourself not to appreciate them, because you already think about new tasks or problems or about your next step you want to achieve. Concentrate in your diary on those achievements to collect positive experiences, don't mourn missed chances. Be patient, persistend and self critical while you walk on. Organise a person non wailing strategy. During a hard time you can read about your achievements in your diary. There'll always be setbacks. It might be necessary to check your goals and to change them. Perhaps you've taken on too much.
"Sport makes it clear, that you can lose on one day and can win the next."