This is a really deep question, I had to think about this one in quite some depth.
Ultimately, my purpose is to do my best to make the best life for myself, my wife, and our future family. It’s super cheesy, but it does give me a really strong motivation to plan forward and ensure that I am working towards that goal. This then stems to my work/research life, where I want to do my best to research things that may help people in distress, or to help prevent that in the first place. I get to use the things that I am good at to try to have a positive influence on the world, which I think is a nice purpose for my work.