What a great question! I've been retired 3 whole months now, and have been going through being totally bored to not leaving the computer, to sewing constantly. I am finding that I really need to feel like I'm doing something worthwhile and not wasting time. I've made blankets for Project Linus for a long time, and now I'm on a terror with that.
I can't sit and watch TV without having something to work on so I can accomplish some that way.
The other thing I've noticed is, I am now finishing a few things I started long ago. I am terrible at that so it has become a goal to finish at least one thing for every new thing I start - well with the exception of the PL blankets. Those I get done.