Big warm welcome to the forum, Nana, from Beautiful British Columbia Canada!
The biggest one for me... not adding too much to my plate.
All too often people try squeezing every single ounce of time and energy into making, doing, seeing, buying, entertaining, and everything in-between, and aside from there being nothing relaxing about that sort of approach, it's encourages stress.
The key for me is planning, and in advance, not last minute planning.