I need more post-its

I have what is often called a 'single-tasking mind'. That means i'm very good at focusing very intently on one thing, but I really suck at dealing with multiple things at once.
Some say this is genetically encoded in men from bygone days; men, being hunters, needed to focus intently on the prey they were hunting, whereas, women, being gatherers, needed to take in a wide swath in order to see all the berries, etc., making women good 'multi-taskers'.
I guess it makes sense, but I don't really know.

What I do know is that I can't keep an idea in my head if a new idea comes along. I'm like a dog getting a new treat; I completely forget about what I was doing 2 seconds ago. This causes Mrs Schwartz (the queen bee of multitasking) all sorts of aggravation. She asks me to get her a glass of water as I go out to the kitchen. I come back without it. "Where's my water?" "Oh yeah, forgot."
I've learned that, when something pops into my head, I need to write it down immediately or I will forget it. Sure, I'll remember it later on when it pops into my head again, but that doesn't help much.