One of the most noticeable differences is what you read. Suddenly any business productivity meme doesn’t make a lot of sense. Your really don’t need to be more productive in business do you. Reading takes up much more of my time. You look at your own library and see all those gems you had collected over the years that you now can get acquainted with. Imagine time available to actually re-read all those classics!
That means those email subscriptions need another viewing and by unsubscribing you notice your in-basket has a distinctive personal feel about it. You aren’t living by the clock anymore, your daily cycle is spent around preparing food when you get hungry.
Retirement is the unusual, slowly become the usual.
Tinfoiling 
All very nice for a few months. Contact me when you get bored. I may have something of interest to you. Dave