Prefer this over "what do you do?", because of the implicit "for work". Some people don't work. Some people's jobs are only so they can afford food and healthcare, and their real passion lies elsewhere!
Plus, the "you" in you have important things to say applies to everyone, and this is a great way to find out about niche interests! active listening and follow up questions will lead to interesting conversations 100% of the time.
I had originally heard the suggestion as "how do you spend your time", but "what keeps you busy" is more succinct and overall less-weird. It was suggested by Nick Disabato[1] in the Garbage Day Discord.