Too old to cut the mustard

As far as I'm concerned, Trump and Hillary are 70 and Bernie is 75. Yes, I'm rounding up a few months for the men, and 1 year for the woman. This is too old for such a demanding job. It's fine for being a part timer, or retired, or an artist or musician who has a manager, or being CEO of your own business. I just don't want those tired and inactive brain cells making global decisions.

https://www.youtube.com/watch?v=R-l2GgSkA6U 
Too old to cut the mustard by Ernest Tubb and Red Foley 1951

I used to could jump just like a deer 
                       
But now you need a new landing gear
                       
I used to could jump a picket fence 
                            
But now you're lucky if you jump an inch