As somebody who is on the plus side of 50, I work hard to make sure I can get to third. It is part of my professionalism and practice as an umpire. I go out the field by myself when no one is around and work on my positioning and mechanics.
Yes, I huff and puff practicing those rotations, but I owe it to the people who expect me to do my best on the field. Yes, I feel more and more like I run like an out of control flamingo, but I still work to have good hustle on the field. I can follow a B/R around first and into second. Yes, I am finding twinges and tweaks in my knees, legs and back that I never had before, but I still try to get out a couple times a week during the off-season and go for 1-2 hour walk.
If you are over 50 and think that a beer, bag of chips and a big chair in front of a tv is the way to prepare for the season, you are not doing anyone a favour. You are definitely not doing your health a favour. I enjoy umpiring because it gets me out and active all year round, not just in the spring and summer. I hope I can stay active enough to do it into my 60s too.