I am in the same place as you. I always enjoyed the gym (weight lifting); practicing and playing guitar, which I would do for hours on end; driving to a park, or the beach and just sitting watching people.

Now none of that matters or interests me anymore. I sleep until 10 -11 am on weekends because I have no reason to get up. When I do get up I go to the recliner, pull a throw over me and just stare into space. It's worse because I hate that routine and what I've become.