I think a lot of it just depends on your personality. My maternal Granddad retired at the age of 55, in 1971, to care for an ailing relative that they had moved into their house. She died within a year, but Granddad never went back to work and never regretted it. Now, he did plenty of other things to occupy his time. He and his brother in law did sort of a shadetree mechanic business out of Granddad's garage...at least until emissions controls and computer equipment got too complex. Granddad also raised a pretty big vegetable garden, and they did a lot of canning and such. Granddad also did most of the housework, cooking, etc, as Grandmom was still working. And, they also had a rental property that required work on a regular basis.
Now, when Grandmom retired, it was a different story. She went out in 1980, at the age of 56, but she was sort of forced out, as the hospital she worked at closed down. She was the workaholic type, and wasn't ready to give it up, so she went back to work. First, out of the home, doing transcription work and other paperwork for some doctors and nurses she knew. Then she went back to work part time/on call at another hospital, and they'd give her as many or as few hours as she wanted. She finally gave that up at age 70, in 1994. And then, with nothing to do, promptly went into depression, thought she was running out of money, etc, and had to get committed!
Grandmom has a cousin who also retired around 1980-81, and around the age of 56-57. She never went back to work, but always found things to do...throwing pool parties during the summer, other parties at other times of the year, going to various social/senior citizens groups, running a little junk/curio shop, etc. That kind of stuff kept her young, I think. She just had her 90th birthday earlier this month, and is still active and spry, still drives (and not in a scary fashion) etc.
My Mom and stepdad both retired in 2011. Mom was 62, and my stepdad was 58. They both carry on about hating it, and second guess themselves regularly, saying they should have kept working. Nevermind the fact that, at the time, both of them were hating their jobs with a passion and chomping at the bit to get out. I can remember how miserable they were, so I think they're just looking at the past with the proverbial rose-tinted glasses.