It's really heartening, but not all surprising to hear these many stories of a happy retirement. Mine was sprung on me a few years ago but I was already beginning to think of leaving. I now know that I had a misguided sense of duty to continue until the bitter end. I can honesty say that that the last couple of years have been the best of my life.
It's truly liberating not to have the obligation of work and the initial feelings of guilt at doing precisely what I please each and every day have long since vanished. I had a fantastic 30 years in the Service but that was a different life and I have moved on. Embrace retirement as soon as you can afford it (and you'll need far less money than you think). You're only here once!!!