All interesting posts, some of them very thought provoking.
From the side of the newly retired, I think quite a few of us who are in good health would enjoy some work, but I promise that there are not squadrons of employers waiting to hoover up the 50+. Most would require some re-skilling; vanishingly few would want to work full time and be at work's beck and call all hours. Heavy physical work wouldn't be an option for most, especially over 65s.
My DSis returned from a senior HR job in the ME when she was 60, and required to retire. All she could find in the UK was retail, and the demands grew more and more exacting as the company discovered how reliable and competent she was. Then it turned into "You must come in at 5:00am to fill shelves until 10, and tomorrow it will be 2pm until closing" and "do you want to be a supervisor?" Err, no, she replied, here's my resignation. So instead, she does some school drops and pick ups for her DGC and drops in daily to make sure our DM has groceries and a chat and helps organise the utilities etc because at 89, DM isn't good with IT beyond email and solitaire. I fear the local council won't know what's hit them if she stands for election as she's threatening!
DH is already working past retirement because he's reluctant to see the company he founded cease trading. It's successful, but too small and specialist to interest a buyer. And he has plans to start another after he has retired, because he thinks he'll be bored. No hobbies he's desperate to pursue and we can't spend all our lives on holiday. We're all in decent fettle, with some health issues but nothing chronic. Some of us have pensions, either state and/or company, and some are better than others: BIL has one state pension from working in Europe for about 10 years that is double his UK state pension. The UK state pension is very niggardly, but future generations will benefit from auto-enrolment systems if the state pension is scaled back.