How do I make my dad put on deoderant?

This is a tough one due to his age. Is he depressed ? I just can't imagine why someone would not want to smell better-I have known people like this and I just don't get it. It's like they don't want to do anything to make themselves feel better-like they are punishing themselves for some unknown reason. An example= I know I am fat and not pretty, no guys like me so why bother to do anything ! I just don't care any longer how I look or smell or feel ! You get what I am saying ? I wish I had better was to help. I feel for your dad.