Kidney stones were a long time ago now, I've been continuously evolving since, and I've been super lucky to have a lot of help with both the cooking and research along the way.
One thing I learned specifically from that incident was that:
Raw spinach != Cooked spinach.
Specifically, the former has a specific chemical that will cause kidney stones. This is problematic for someone on the subway diet who substitutes spinach for the lettuce, because, you know, spinach is healthier than lettuce... which is kind of true, until it isn't.
Edit: what was easy? Knowing the impact that little daily decisions can have (a few day stay in the hospital). Also, cutting out the soda was easy after experiencing that level of pain (the kind where things become a blur, you accidentally rip out IVs, sister passes out just from watching, etc).
Also, I've changed my diet regularly as information changes for the past ten years. Every single time I thought I was "being the healthiest I can be." That said, I'm not suggesting a specific solution. What I'm suggesting is becoming familiar with the practice of iterating on your eating habits to maximize your life (in more ways than simply extension).