I think it was her own invention.
Aunt D would love being remembered and written about, but she would hate the title of this post. It could be read it as me saying that she was old. I will specify that she was not old when she began using the saying, it's just that she said it enough to become an old saying, of the aunt-ish variety. Which only implies that she's old.
She picked up a hatred of aging from her mother, my Grandma. Grandma picked it up from her father, although it was also probably a standard tenet in her social group. Her father used to say that a woman who would tell her age would tell anything. I learned this from my Father who used to complain about his relatives as a regular thing. Grandpa P died long before I was born. When Father would talk about his sayings, his voice would tighten into a sneer. He complained that his mother took them too seriously.
"From his lips to her heart," he would sneer. "With no thought at all." Of course, it didn't help at all that the sayings had been either aimed at Dad, when he was young, or used as trump cards in arguments with him. The only other one I remember, really, is "Laugh before breakfast: cry before supper." I've never heard it anywhere else and I agree that it deserved to be ignored.