I think there's a few different elements to ceasing to work with having something to replace the time with and finances as part of it. I think also, for singles, it can be a social thing as well. We're all different and have different needs and situations.
For me, I'll have so much to do (so much I'm unable to get to at the moment) and I think I'll be fine. That's not to say I'll never go back to work, I may, but it'll be different I think due to not having to be there. For now I work though and it certainly feels a little different now I'm set on an end date, life seems to have opened up a lot. It's a difficult thing to describe.
With regret, I think it's good to see it, feel it, as long as it's put into perspective which is what I try to do. Holding onto it though, well that only causes the event/situation to have a hold still. Just my opinion.
I understand about it being different for everybody. I knew a woman a few years back that retired from the company I work for at 70 years old. In a year she came back and said she couldn't stand doing nothing. Some of her co-workers thought that possibly what she couldn't stand was being home 24/7 with her husband, who was already retired. I got a laugh out of that, but who knows.
I have never been one that thought I would have nothing to do if I wasn't working. I know plenty to do on my own and if not, I have friends that go places as a seniors group and they have a lot of fun, so to me, there are plenty of things I'd love to do if I weren't working. I cannot even imagine being bored for a minute !
It is very true, there is no valid use in holding onto things that can't be changed.
I've heard similar stories and have been warned about it, but only by peopp who don't know me well; those who do know what's up. Like you, there'd be plenty to do.