Personal Statement Topic Trouble

I have one good personal statement prepared. I took a look at it a few days ago and was satisfied with what I had written. I've been trying to a second one that deals more with my motivation for applying to law school. For whatever reason, every time I've tried to write about this I get off on totally unrelated tangents that add nothing to my statement. I think I've been focusing too much on the external factors on why I've been thinking about becoming a lawyer with a science background rather than a pure research scientist. Maybe that will be a good place to start. My identity as a scientist and how that identity formed. Maybe I can note a couple of things that made me start to take a second look at my career and what I want to achieve. I switched to this venue to break my brain lock over in word. Maybe it actually helped.