Age 63, reasonable age for retirement
If in generally good health, I think 63 is reasonable.
Retiring in the 50s, at least for me, was not a favorable decision. 63 would still allow someone to work part-time a bit and then qualify for social security. Of course, this all assumes one has enough savings, too. I am now 59 (soon to be 60).
If I could go back to my retirement age of 57, I would never have retired. I was a workaholic and had no outside social life.
Don't let me scare those of you who have healthier lifestyles.