To be able to concentrate for ...

To be able to concentrate for a considerable time is essential to difficult achievement.
To be able to concentrate for a considerable time is essential to difficult achievement.

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Being self-made is a state of mind, and once you put that mentality to work, your success will come.
 Dave East
A lot of people change for good. Some people just fall off. Just trying to progress in anything, no matter what you're doing, I feel like any progression you make... some people aren't gonna be around you that were around you.
 Dave East
There are no secrets to success. It is the result of preparation, hard work, and learning from failure.
You have to have the service mentality in the sense that you subjugate your own ego, and you subjugate a large part of your own life to really helping other people, being successful on their behalf.
 Herb Kelleher
Success consists of going from failure to failure without loss of enthusiasm.

Quotes from the same author

Collective fear stimulates herd instinct, and tends to produce ferocity toward those who are not regarded as members of the herd.
We may say, in a broad way, that Greek philosophy down to Aristotle expresses the mentality appropriate to the City State; that Stoicism is appropriate to a cosmopolitan despotism; that stochastic philosophy is an intellectual expression of the Church as an organization; that philosophy since Descartes, or at any rate since Locke, tends to embody the prejudices of the commercial middle class; and that Marxism and Fascism are the philosophies appropriate to the modern industrial state.
To conquer fear is the beginning of wisdom.
The happiness that is genuinely satisfying is accompanied by the fullest exercise of our faculties and the fullest realization of the world in which we live.
Real life is, to most men, a long second best, a perpetual compromise between the ideal and the possible.