If driving solo, I say "the garage door is closing" as I'm backing down the driveway so I can hopefully remember I closed it when I'm 5 miles down the road and doubt sets in.
I do this if I'm alone and ESPECIALLY if my wife and/or daughter are in the car. They will be yapping and I deliberately interrupt them so that they are also aware that the garage door is closed (saw it go all the way down and not open again).
I've done this too. It works, but I get laughed at - so that's a bonus...
I get this. I'd set up an IP camera so you can verify on your phone.
Believe it or not, I don't carry a phone.
You are blessed.