Do you have a school oath?
In a capoeira club I trained with (Capoeira Rosa Rubra), we would always form a circle and recite a saying before and after class:
"Cada dia que passa, estou melhor em tudo que fasso"
"Each day that passes, I am improving everything that I do"
I love this saying and I think it's one of the most direct and straight forward affirmations. It's so simple, but if you uphold this virtue and improve even one thing you do each day, there are so many other things that will fall into place. This is taking responsibility for the outcome of your actions and saying, next time I can do that even better - no matter how good you are!
Beginners can stay motivated with this phrase, and experts can stay humble.
Do you have an oath at your school? What does it mean to you?