You have a stronger constitution than I do. I'm a vegetarian. 95% of the time, anyway. But I can't go full-on vegan. I just can't do it. I like pizza, mozzarella sticks, string cheese, and ice cream too much.
IIRC, you're exactly the same age as me - 39.
I originally became a vegetarian at 13. I became a vegan when I was 17. It was originally just a New Year's resolution - a test of willpower for a single year, since I knew so many people in high school who tried it and "broke edge" after only a few months.
But once I became a vegan, my whole diet - my whole relationship with food - began to change. Even after I became a vegetarian there were lots of vegetables I didn't like, and I subsisted a lot on pizza and veggie burgers. But pretty soon after becoming a vegan I learned to love just about every vegetable (except celery, which I still detest to this day). After a year of it I felt healthier and was enjoying being a vegan, and saw no particular reason to stop. And I have not to this day. I've accidentally eaten things with dairy in them a few times, but never knowingly ate anything non-vegan in 22 years.