Source: University of Texas (Austin) website, date indeterminate
Finally, I must at least address the question of whether greatness is worth the large effort it requires. Those who have done really great things generally report, privately, that it is better than wine, the opposite sex, and song put together. The realization that you have done it is overwhelming.
Of course I have consulted only those who did do great things, and have no dared to ask those who did not. Perhaps they would reply differently. But, as is often said, it is in the struggle and not the success that the real gain appears. In striving to do great things, you change yourself into a better person, so they claim. The actual success is of less importance, so they say. And I tend to believe this theory.
No one ever told me the kinds of things I have just related to you; I had to find them out for myself. Since I have now told you how to succeed, you have no excuse for not trying and doing great work in your chosen field.