"Knowledge: If I were to go vegan, I would be unsure how to go vegan safely for an extended period, and how to make sure I got a decent variety rather than eating the same foods over and over (which comes into taste - I don't mind vegan food but there's much more variety I can find in meat-based dishes)"
If knowledge is one of your preventative factors, I have been vegetarian since 2005 and vegan since 2015. I am happy to help. I compete in various sports and am in good health. I am happy to communicate with you directly and provide evidence of such claims if that helps quell your concerns about "[going] vegan safely for an extended period."
I would ecstatically give you my time in the pursuit of sharing knowledge and helping to reduce barriers to veganism.