A successful tool is one that was used to do something undreamt of by its author.
“If you don't look like Rupert Graves or Hugh Grant, they'll have you playing the gardener.”
“I enjoy those small chats you have when people come up and talk to you about your work. It only involves a few seconds of effort to be nice to those people, and I am very grateful for the kind words that people have taken the trouble to express to me in person.”