Stopped eating meat
Although I had long been disabused of any paranormal faith, in a world unfriendly to secularism, I described myself as “culturally Catholic”. So it was natural, when I realized a week after Ash Wednesday I’d not eaten meat yet, for me to give up meat for Lent. It was an experiment to see if I’d feel more or less fit; I really had no expectations.
When Easter came, I observed that I’d had a bit more energy than normal. So I never ate meat again. I did not start eating healthy, per se; I was a connoisseur of fast-food fried fish products.
I eventually learned this made me a pescatarian. Only after moving to Seattle with Shannon did I gradually give up fish altogether and start describing myself as vegetarian.