I was like you...afraid as to how I was going to fill up my day.
I had a physically demanding job. It took me about 4 months to feel rested. I belong to a drop in quilt group and i clean our church once a week. I go out for lunch about once a week. I plan yard sales with my grandson. If he is busy, I go by myself.
Last week DH went! (found a Singer 101 in a barn attic!)
I do not read or watch TV as much as I thought I would. I do A LOT of quilting and have a nice shady yard.
One thing to be careful of: saying NO to people. Just because you are loose during the day, some think you want to run errands for them.