As one of those very early retirees now going on year 14, I'll admit to be being envious of those with huge passion or all consuming hobby. My dad retired at 55, and immediately threw himself to building a wooden airplane. 7 years later he was done and fortunately enjoy 10 years of flying (and tinkering with it) before dying pretty young.
I honestly expected to find a second career (paid) after a few years, but it didn't work out that way. Mostly because I am lazy but partly because, companies doing cool things hatch everyday in Silicon Valley and not very many in Hawaii.
Most of us on the forum had a careers not just jobs,and our work provide meaning and a sense of accomplishment to our lives. Plenty of people say they'd be bored not working and I sort of understand that. That hasn't been my problem, but I do get the lack of accomplishment or purpose.
I have finally come to a few conclusions. Your best months or maybe years working will probably be better working than retirement. The sense of accomplishment when the project you work is successful and your peers and bosses pat you on the back and give you raise. You just do not get that in retirement. Recognition is really just something you get from a spouse or family. Now people who go on great adventures like Sarah,or become heavily involved in overseas volunteer work they may get that sense of accomplishment. I think for the rest of us not so much.
Volunteer work can help but it isn't quite the same. Partly because for the most part it is hard to find volunteer work that really is intellectually challenging. Of the 1/2 dozen volunteer jobs only couple have provide much intellectual stimulation. But even then nothing quite says, "Clif you did good" quite like bonus and/or a raise.
On the other hand, your worse month or year being retired is absolutely going to be much better than your worse month or year working. There is absolutely nothing I miss about worrying about layoffs, firing people, giving poor performance reviews, or ranking and rating sessions. Likewise I'll miss nothing about dragging myself into a 2 hour staff meeting, that is a waste of time or dealing with a bad boss. The feelings of stress and exhaustion are so minor in retirement that few times I've felt that way in retirement, simply recalling the bad months working brought a smile to my face and feeling "Damn I am lucky I am not working" I also don't miss being force to prioritize work over my own needs or my family. And I don't even have kids, I can't really imagine how bad it would if you had miss a big day in your kids life, cause the job demands you be out of town. When something goes wrong in the retirement it only effects you and your family, work failures impact lots of others.
So retirement for me has resulted in lower highs, but much highers lows, and on average I am happier.