One trick that I’ve always stood by is having an extra supply of something and pretending it’s not there except for in case you need it in a pinch. For instance, I have a savings account that I never touch unless I’m looking to make a particularly big purchase. I try to make certain that it never gets any lower than a certain amount, so I always have a safety cushion.
I do the same thing with supplies that need to be replenished. For my boat, I keep a Mercury oil 55 gallon drum in my garage as an extra amount that doesn’t need to be touched unless I’m going on a boating trip on short notice and I don’t have the time to pick up more oil. I rarely have to take oil from it, but it’s really nice having the oil drum as a safety cushion, just like my savings account.