"Two old folks' Joke" joke

I heard these from my father, who heard them from a friend, etc.
They're definitely not original.
A young man is jogging through a park when he sees an old man sitting
on a bench sobbing. Concerned, he stops by the bench. "Is there anything I can
do for you, sir?"
"Oh," sobs the old man, "everything's wonderful. I just married a
gorgeous twenty-year old who'll do anything for me, and even my children love
her. We have a beautiful house, a pool..."
"So what's the matter?" the puzzled young man asks.
"I can't remember where I live!"
Three old ladies are sitting in a diner, chatting about various things.
One lady says, "You know, I'm getting really forgetful. This morning, I was
standing at the top of the stairs, and I couldn't remember whether I had just
come up or was about to go down."
The second lady says, "You think that's bad? The other day, I was
sitting on the edge of my bed, and I couldn't remember whether I was going to
bed or had just woken up!"
The third lady smiles smugly. "Well, my memory's just as good as it's
always been, knock wood." She raps the table. With a startled look on her face,
she asks, "Who's there?"