Harry Potter: How come wizards die so old?

Why do wizards die so old? Like Dumbledore was killed at the age of 116 and Grindelwald was killed at the age of 115 so if they left them alive they would have lived for much longer. How is that? I know Dumbledore didn't use an elixir of life because he destroyed the philosophers' stone and he obviously didn't have a horcrux because he died right away and please don't say he he casted a spell on himself because there is no such a spell that prevents Death from coming unless he is actually wearing the invisibility cloak of the Deathly Hallows (Harry's). Why do they Live so long then even though they are supposed to be mortal? Thanks in advance.