I'll be 60 in a couple of weeks time (I hate typing that - get off my lawn etc!). I know I'm not less productive now than I was 10, 20, 30 years ago. Maybe a bit more cynical - but then I can hide that with humour.
The one think I do feel strongly is that my current FTE job is my last one. Ageism is a real issue, when it comes to finding a job in tech when you're in your 50s; running the recruitment race in my 60s is not something I want to face. Which means I feel like I've lost the chance to walk away from my current job if anything goes wrong.
I get my pension in 7 years time: I'm looking forward to it already!