Veganism isn't a fad. It's a lifestyle, and as with any lifestyle change, it requires a strong WHY.
Why do you want to be vegan?
Your why might be related to ethics/health/environmental or anything else. The why is very important for staying accountable and for navigating the many "but why?" questions your friends and family will ask.
It's also important to stay updated on the other side of the argument, on why veganism isn't the right choice for everyone. This is not only helpful for making the best decision for you, but also, "being forewarned is being forearmed" and you will be asked to defend yourself here and there.