It's a strange thing, but once I had enough money, it was easier to spend less. Because now I'm more able to look at the total picture, and see that it's not difficult, and even rewarding, to live on little money.
It was Jacob at ERE who mentioned that all these financial people ask "how much do you need to retire", while he asked "how little do you need to retire". When I read that, and thought about what Jacob said, I thought, how brilliant.
It may be a little turn of thinking about something so important as FIRE, but it turned my world upsidedown.