I had a reasonable retirement planned and then forces out of my control threw everything upside down!
I am now officially retired, but I never planned to be in my current situation when I began my retirement. Last year, I began drawing Social Security since I was at full retirement age and thankfully my amount is a higher tier as I had an above average income for most of my career. The thing that threw everything out of whack was me being laid off twice last year. So here I am beginning retirement and wanting to work just to keep me and my mind active, but can not find parttime work that will keep my weekends free so I can see my grandchildren, as one of them usually spends the entire weekend with me. It would kill us if we could not spend the weekend together.
So I guess my two cents is that regardless of your retirement plans there are too many outside forces that can throw you for a loop.