I'm going on 63 and when I retire, I plan to get a part time job
and still use the skills I've aquired in life.
If I can't find a job, I'll volunteer my help.
I've a buddy who retired 3 yrs ago & he volunteers at the local National Aquarium, learned to be a tour guide, & does that a few days a week.
He also volunteers at one of the local Animal Shelters helps feed, groom & take care of the animals, and helps people find new pets from the ones they constantly get (but he has adopted a few more cats than I think he needs at the moment- seems to want to bring 'em all home ).
He & his wife (she still works, full time- he takes her to work, and picks her up- everyday) have a sailboat and belong to a boating club, have made friends there, and he helps others fix their boats (if ya got a boat- something always needs fixin') as well as they socialize at the club.
I think the key is to keep a full & busy schedule, with allotted time for 'nothing'. That way boredom and the 'rocking chair' syndrome doesn't
have time to take effect.