It's a question I'm training my brain to ask itself every time I'm about to do something I might regret later. For example, when I'm about to buy something, watch a video or click on a link.
It's incredible how many times this simple question prevents me from doing things that won't add any value to my life.
These are clearly not major things, but are just drops in the sea of tiny, insignificant interactions. This question makes my daily life more pleasant, enjoyable and in some ways more meaningful.