When you're still sitting in your car on the drive, an hour or even 2 after arriving home.
When you stay sitting in your car on the drive until the time you have to set off out somewhere again.
When you call the DCs by the pets' names and vice versa.
When you put the pet food in to the bowl already full of their drinking water.
When you're looking at baby clothes in a shop, rocking as you do so to sooth your baby, and people are looking over to admire your wonderful mothering and beautiful baby, except the baby is at home or in the car with the family.
When you just can't get out of bed, despite being desperate for a wee and a drink, perhaps also paracetamol and a hot water bottle, or perhaps making yourself late for something.
When you drive around your village with your house keys, purse and phone on your car roof.
When you search for ages for your specs, even asking for help from others and getting quite cross that you can't find them, and then someone points out or you spot in the mirror that your specs are on your head.
I have a lot more.