pit: keep working or enjoy the life long vacation

Guess I am old enough to start thinking this topic. 

John, the COO of ABC inc. is retiring this month, but this morning he sent out an email that he will keep working in the company after this month at reduced hours, 3 days/week, still on the COO duty, no deadline. John has worked in the company for over 20 years, he had been in project management, plant manager, and also get involved deeply in customer and supplier relationships. So difficult to have his replacement, a long transition period is aniticipated.

John lives in over 1 hours driving distance from his work place. He is healthy and energetic, no physical or mental restriction  for him from keep working.  He has achieved debt free for long time. Retirement is not a problem.

What option you think is better if one person reached the age of retirement with no financing or health problem. Opt 1. keep working. Opt 2. retire, enjoy life long vacation.

We like vacations or weekends so we can have breaks from work.  Isn't it because of through comparison to the stress of work then we feel vacations and weekends so precious?  Would vacation and weekends be still the same good if everyday is a vacation or weekend day?  I knew a few people died very quickly after they retired.  I am definitely not a minority from this aspect.

I consider the mental status playing a big role in life. If the body is tuned up for the busy working paces an abrupt routine change can have big impact to the system. 

I think human mentality is rooted problem solving and accomplishment. So working can be satisfying. The feeling of usefulness is a vital support of human life. 

Makes me thinking about my father, a workaholic, tried to keep himself busy at all times; I felt he would stop living at the moment he stopped working. So after he finished his last job, his grandson, my sister's son grew out off his arm, he collapsed. 

Now myself, I never feel I have enough time to do things I like to do, l have to works, I have so many hobbies I owned so much debt from my hobbies, the good debts I am eager to pay back.

Even so, I still don't know if these hobbies could fill me up after my retirement. I feel a little bit tired of work once in a while, I am longing for Friday from Monday, maybe only because I didn't realize that work is equally or more important than leisure? ? ? ?

One thing I am sure is an empty mind with nothing to do won't last.

Thus I don't know if I ever want to leave work whenever I am still in good physical and mental shape.  Maybe I will surely know when the time arrives.

Please give your opinion,   thoroughly appreciated