try a side project? when I think of fun ideas, I always notice how easy it is to bump into computationally hard or complicated stats/ML/math problems left and right, even if it's just a simple game.

I remember one time when I realized this: a TV show character suggested building an app that lets you take a picture of someone's shoes and then give you links where you could buy them. It sounded a) like a pretty good business idea and b) crazy hard to build (the time the show aired was before the Deep Learning proliferation iirc).