Not every difficult and dangerous thing is suitable for training, but only that which is conducive to success in achieving the object of our effort. – Epictetus

The talent of success is nothing more than doing what you can do well, and doing well whatever you do without thought of fame. If it comes at all it will come because it is deserved, not because it is sought after. – Henry Wadsworth Longfellow

The measure of success is not whether you have a tough problem to deal with, but whether it is the same problem you had last year. – John Foster Dulles