The Need For Strong Motivation:

https://www.webofstories.com/people/francis.crick/80?o=SH

"You must notice that people who make a lot of money are people who are interested in making money. They don't even need the money usually. They go on making the money when they got masses of money. It's just the same thing again. If you want to make money you really have to be interested in making money. ... You have to have a strong motivation to do it: 'That's the thing I really want to do and I don't want to be bothered with other things.' "