.
Almost none. My grandpas have remained the same way as they were in their sixties and seventies. I don't expect change from them now.
I'm 78 and who I am ever going to be I already am! Thank you for your reply Oscar! :)

70 was the age at which I realized that all my accomplishments were behind me. I still daydream about inventing cold fusion and warp drive, but that's it. I can't even jump up and yell "Eureka" any more. I only struggle to my feet and chuckle weakly.
anything's possible