Celia Green has an aphorism, "Only the impossible is worth attempting. In everything else one is sure to fail." I don't actually know what it means; perhaps it is an assertion about futility ("failure") being inherent in all ordinary purposes. But she has written a lot about the psychology of extraordinary achievement - how do to "impossible" things. A hint of it can be seen in her account of having teeth removed without anesthetic. Elsewhere she writes about utilizing self-induced psychological tension to compel herself to solve problems.