Of course, there are always stationary bikes you ride in the house...
Back to the point, it would be a lot easier to plan if you knew the end date. All you have is a rough guess, but you know it is not likely to be past 85. And even then, your life is likely very different in your 80s.
So, FIRE when you can, not when the company tells you, you can.
Of course I wonder why I am not FIRE'd yet too.
FIRE no later than 7/5/2016
at 56 (done), securing '16 401K match (done), getting '15 401K match (done), LTI Bonus (done), Perf bonus (done), maxing out 401K (done), picking up 1,000 hours to get another year of pension (done), July 1st benefits (vacation day, healthcare) (done), July 4th holiday. 0 days left. (done) OFFICIALLY RETIRED 7/5/2016!!