The thing with RPing characters over 60 is that people don't like losing RP. Sixty-year-olds may still be as fit as they were as forty years old but the vast majority is already feeling that their aging process is beginning. They do not like RPing not being "Young, perfectly in shape and ready to take on the world." which is why they make mistakes RPing children in the first place. You need to be ready and willing to accept that you're not Mike Tyson, RPing immersively is the key to properly RPing children and/or old people but people just don't want to.