"you're not as clever as your brother", "I don't think you have what it takes to work in a school", "who are you to teach me?!"
Confidence is not a strong point of mind, I have this huge sense of inadequacy. But when a friend suggested I start tutoring I didn't have the confidence to keep putting her off, so in the end I agreed. That was back in 2012 and the company has grown so much since then. (My confidence hasn't but that's work in progress). If you lack confidence and you're considering becoming a tutor, maybe this will give you the hope that you needed that maybe you could do it too.