Tennis is a lifetime game as it needs millions repetitions to be successful.
Here are some subjective reminders leading to high performance:

• Don't aim for technical perfection. If it's good enough it's good enough. Make it unconscious competence so the body can intuitively repeat the motion during match
• Go last mile by working the serve on chill day
• Play more training matches or count points to replicate tournament condition
• Sprint session during day off instead of running "marathons". You already run on the court
• Constantly research the game strategy and tactics
• Eat anti-inflammatory diet and drink clean
• Build a todo-list before every training
• If different players report the same issue in your game then seriously think about it
• Watch tennis, all levels
• Double-check racket and string setup with a pro based on your level, playing style and weather condition