I reminded my human that it was time to clean my litter box yesterday, and it worked.
He had let it go for a couple of days and it needed attention. It is in the bathroom, at the bottom of the shelves. I sometimes like to sit on the top of those shelves, but I need to jump on my human's back to get there. He'll often bend over to give me a better halfway landing spot. When he does that, he's looking right at my litter box.
So yesterday, I get up on the lavatory, or bathroom sink if you prefer, and looked longingly (didn't he play for the Chicago Bulls?) at the top shelf. He bent over, and I jumped on his back. When I was convinced he had looked at my litter box long enough, I jumped down to the floor. He then changed the litter completely.
When he left the bathroom, I made sure that it was clean. I dug three or four pits in it before I finally used it.
This is a file photo of me in my litter box, and me on the top shelf as seen from the shower where the human likes to stand in the rain.