Here is a rule I’ve used over the past year to avoid spending money on that which I want, but do not need.
When I see something I’d like to buy (that falls outside of “baseline expenditure” of rent, food, transport, books, and experiences), I set a reminder in my calendar for 2 months.
If at the end of the 2 month period, I still want the item with the same fervour, then it passes the test, and I buy it. In other words, it’s more than a whim.
Most of the time, 2 months down the road, I no longer want the item.
This rule ensures the physical things in our lives are of real value, and helps us avoid the clutter that comes with accumulation.
But perhaps its biggest benefit is in preserving optionality: I can do something in the future with the money I didn’t spend today.