Declutter, or start a use-it-up mission on, something that you constantly pass over to use a similar item instead. This might be a toiletry item such as a hair product, hand cream, body wash, purfume etc. Or maybe an ingredient in your kitchen, or a crafting medium, or even something as simple as a pen you don’t like the flow of… I am sure you can think of such an item.
I am going to set myself a challenge to use up some of the cardstocks in my craft stash that I never use. And maybe some embellishments too. To be honest, I suppose, I do this all the time because my whole craft stash is a use it up mission for me. But there are some colours that I prefer that I am beginning to run out of, so this mission will delay the need to replace them.