I love this guidance from James Clear (acclaimed author of Atomic Habits) and believe it is especially relevant at this time of the year.
Something I try to remind myself:

In a sense, what matters most is how you respond on the bad days, not the good ones. There will always be very challenging days as we get to this stage of the year.

•    Anyone can smile when life goes smoothly.
•    Anyone can train when they feel great.
•    Anyone can be kind when the relationship is easy.

It’s how you act when the situation isn’t optimal that makes the difference.  Hang in there and Finish STRONG!