Motivation is an interesting one.
We can quote Ghandi, Aristotle, Marcus Aurelius, Mother Theresa, Churchill, Nightingale (Florence and Earl) etc.
Motivation doesn't come from without, it comes from within. It is deciding what your top value is right now and aligning your behaviours with that value (or two).
What are your number 1 or 2 values and what behaviours are you aligning with them?
How else do you motivate from within?