Never say never

How do you train a dog that has marked spots of territories in the house all his life to give that messy habit up? Likewise, how do you get a person who is nearly 60 year old to change his temperament and be a nicer person to live with?

Just like how some people repent and receive Christ just before they take their last breath; it is never say never for a dog or a person to be a better being.

I beg to differ the saying of “a leopard can’t change its spots”. Do you?