I'm a 42M and have been eating plant based/no animal products for the past 15 years. I started it to experiment and see if it would make a difference in my recovery while doing high volume training (ultramarathons + IM triathlons). It did, and I felt better, so it was easy to keep it up.
15 years of consistency has also made it much easier to maintain - you get accustomed to a certain way of eating, learn how to negotiate social situations surrounding food, and also learn how to substitute previous preferred foods with healthier plant-based versions in satisfying and sustainable ways.
Some key resources for me over the years have been: Rip and Caldwell Esselstyn/Engine 5 Diet, Neal Barnard, T Colin Campbell, Joel Fuhrman, Rich Roll, Brendan Brazier/Vega, Scott Jurek, Sage Canaday & Sandi Nypaver, Michael Greger MD/NutritionFacts.org, and No Meat Athlete/Matt Frazier.
My overall fitness and endurance have steadily improved and overall objective measures of health (biometric data) are ideal, so I do see myself maintaining this as a lifestyle indefinitely. My wife is also fully plant-based and a multiple-time Boston Marathon and age group Ironman World Championship qualifier on this diet. Feel free to message if any questions.