I wonder too. I'm sure I'm not the only one, who after being retired for a year, honestly wondered how I ever had had time to work!
"Work" helped me manage my time much more effectively than I seem to manage it when left to my own imagination & entertainment...
On a serious note, we're approaching the first anniversary of the sudden death (cerebral hemorrhage) of a friend/neighbor. He and his spouse were in their mid-60s and had the assets to support their retirement lifestyle. However they both grew up in relative poverty, had a strong work ethic, didn't actually hate their jobs, and planned to keep working until they'd paid off their mortgage & car loans. (In his case it was "just two more years".) Both of them were in great health, no issues, no medications, loving life. They were going to use the extra cash to travel, to renovate their home, and to gift the kids. He and I used to joke with each other (over frosty beverages while sitting on his back lanai admiring his view of the Ko'olau) about how he couldn't understand why I'd pass up all that money to go surfing and I couldn't understand why he'd give up all his time for that money.
Until one afternoon he didn't come home from work and died in the ICU a few days later. It was the most painful funeral I've attended since my mother's.
His widow has adult children on the island, and they visit frequently. We've stayed in touch while giving her space. We take care of handyman repairs for her, and she brings us food. A few months ago she taught our daughter how to make pizza and manapua from scratch. Now she's setting aside the widow image, coming out of her shell and trying to spend more time out & about. My spouse has spent the last few weeks taking daily evening walks with her. Depending on the strength of her anger & sorrow, they do 2-4 miles at a pretty fast clip. It's been almost a year and now his widow can finish most of the walks without crying. But they're still dealing with paperwork and benefits and a host of other bureaucratic issues. They'll be solved, but they take time & energy. She's financially secure but she's decided that she's going to work for another year or two... mainly because she can.
One side effect has been that my spouse has come home just about every day for nearly a year and said "Nords, if you leave me a young widow then I'm gonna
kill you." You married veterans know that the only proper response is "I love you too, honey!"
So... for all those who are worried about boredom, I think you're worrying about the wrong problem.