Well I'm almost 77:
You're retired. You don't need to work. You do what you want, you say what you think (except less with relatives and maybe old friends).
You're getting tired of BS. Well, we can say you are just getting cranky, - but it is really more than that.
You can probably still lift weights, but are slowly learning not to overdue it because:
1. Recovery takes longer.
2. And the older you get, the longer the recovery takes.
Which in turn forces you to reduce the amount of strenuous activity you do - unless you never really did as much as you could - which, in at least some instances, - may allow you to push yourself further -- and then hope you don't run into a bad day where that can cause some kind of heart attack - like a silent bullet coming out of nowhere.
Your joints and bones start causing problems with nerves, but if you are smart you can probably adjust to that - for awhile.
You learn to compensate so many things: Do exercise every hour or so, like lifting 2x20lb dumbbells 10 times from the floor to overhead, arms out to the side or forward, walk, jog 3 time/week. Rest, meditate, listen to lots of music. Try to do a better job of tolerating other people around you - for what that is worth.