I agree that this has been a great topic.
I retired in May of 2012, after 43 years in Information Technology for 3 major companies. I was directly involved in the early days of the PC, laptops, office automation, graphical user interfaces, relational data bases, large scale 3D printing, 3D solids modeling. Learning new technologies and processes was the norm where I worked, well before change exploded worldwide. Opportunities to learn were never ending (and corporate funded). I worked with a super bunch of people and was able to help most of them grow their skills and advance in their career. When the fun was gone, mostly due to constant pressure to do more with less and move more and more positions overseas in search of lower cost (with usually much less quality), I decided to take an option to walk away that I couldn't resist.
Along the way, I married my best friend, raised a great family, welcomed 5 grandkids, developed many friendships, got hooked on exercise and being active, developed several hobbies (including O gauge trains), got into restoring a 1967 Shelby GT500 and a 1966 big block Corvette, travelled, began volunteering, and lived a comfortable but not extravagant life.
So, no, I don't miss how things were near the end of my paid, working career.
But I do miss the people. I still get together regularly with many of the people I worked with, and enjoy having them, their family, and grandkids over to run trains. I have never looked back and continue to enjoy all the gifts I have received with family and friends.
I am always busy, and enjoy the flexibility to be able to change plans as things come up. Enjoy and share your time, talent, and treasures while you can.