I retired from the Navy and started getting a pension in 1995 -- at age 48! I was in a prime position (with a top secret Special Intelligence security clearance) to join the revolving door military-industrial complex as a contractor and make decent money in the Washington D.C. area for years, but did not want to do that. Maybe it was inherited: my Dad retired as a senior naval officer/pilot at age 45 and could've made big bucks in the same way, but chose to move to Oregon and become a cattle rancher and make practically nothing. But that military pension gives one options.
I am perfectly happy with the retirement life I chose.
Edit: The other thing is that my life in the Navy for the first 12 years (as an enlisted sailor, then a Chief) and the final 13 years (as an officer) were much different. Having gold on my sleeve was nice and all and the money was better, but I missed the direct connection to the work that I had as a sailor.