"Never let anyone tell you that you are not good enough to do something." - Will Smith - What does this quote means?

This quote means to me that if you let people affect your way of thinking you will get no where, just thinking you are what they say you are. its more like a phlacebo  affect

Explanation:

is that lennie, a man with a mental disability, is treated poorly due to his mental disability

d) the narrator even suggested that the white whale, moby d, was ubiquitous and present in every ocean at every moment.