I think that one of the most compelling thinkers that talks about the need for courage and belief in oneself would have to be Swami Vivekananda. A consistent theme in his writings, teachings, and quotations is the idea of fortifying one's view of the world with a sense of courage and dignity in what believes. Consider the following quote:
'Face the brutes' That is a lesson for all life- face the terrible, face it boldly.
This is a great quote to bring out the idea that the stronger beliefs one holds, the greater the chance that opposition will be present towards them. The idea of needing courage to "Face the brutes" is a very compelling message. Another quote helps to enhance how difficulty and challenge necessitates courage in defending one's own view of the world:
'Comfort' is no test of truth; on the contrary, truth is often far from being comfortable.
Swami Vivekananda's idea of "comfort" and "truth" being mutually exclusive at times helps to bring out the courage needed to defend the latter and put aside the former. Swami was able to articulate such a condition in galvanizing individuals into action in terms of their own viewpoint and its relation to the world. Swami Vivekananda brings this out with a letter written to one of his disciples:
It is not the work of a day, and the path is full of the most deadly thorns.
In this quote, Swami is able to evoke the idea of how courage is needed to navigate through "deadly thorns." In these quotes, the requisite courage needed to defend one's own view of the world is brought out in strong fashion.