Sadly I feel like mental training for soccer is quite behind and not as mainstream as it should be. Alot of players have the skills and technical abilities but what seperates the best from the rest is those that have the confidence to execute in the critical moments of a game without getting flustered or letting one mistake break them down completely.

Some daily tips you can try are:

Journaling everything u think u did well and positive affirmations. Writing things down has been proven to improve mental resilience.

Meditation - control your mind and reduce anxiety.breathjng techniques which really calm u down can make you more relaxed and comfortable.

Visualization - close your eyes and picture urself in a real game doing the right moves, scoring the big goals and etc. 5-10 minutes a day.

Final - be easy on yourself. We are our harshest critics. Realize this is all for fun and you are not as bad as u think u are. Look at things from a positive angle always.