When I was working for Microsoft, I used to take cheese sandwiches to work for lunch every day. I like to have salt and vinegar flavored crisps in my cheese sandwiches. None of the vending machines at Microsoft sell such things so I have to take my own. This being the USA, salt and vinegar crisps are generally only sold in big bags which last me a week or more. I generally remember to buy more crisps at the supermarket when I am getting close to running out, but remembering to actually take them to work was, for some reason, more problematic.
I therefore needed a crisp refill protocol. I used to email myself at home when I needed more, so I would remember to put crisps in my bag when doing my morning email. But after a while I found myself forgetting even in the short time between answering my email and making my lunch. I realized I needed to be reminded right when I am making my lunch, and worked out an even simpler protocol - I just put a twist tie in my empty lunch box and then I see it when I'm refilling it. This is even simpler and worked much better (though I still managed to fail to bring in crisps once while using this protocol). This protocol does mean that all the twist ties end up at home though.
Now that I work at home, this is all so much simpler.