I'm sorry you're feeling lost. These words come from sister-retired at 64 and a dear friend who retired more recently:
for the first 6 months don't plan 'stuff' or focus on what. Each morning do what you feel at the moment. Then at 6 months, start considering: 1) things to learn, 2) things to see, 3) places to go-near or far
Best of luck in your transition.