From https://sidsavara.com/why-3-of-harvard-mbas-make-ten-times-a...
“Have you set clear, written goals for your future and made plans to accomplish them?” In 1979, interviewers asked new graduates from the Harvard’s MBA Program and found that :
84% had no specific goals at all
13% had goals but they were not committed to paper
3% had clear, written goals and plans to accomplish them
In 1989, the interviewers again interviewed the graduates of that class. You can guess the results:The 13% of the class who had goals were earning, on average, twice as much as the 84 percent who had no goals at all.
Even more staggering – the three percent who had clear, written goals were earning, on average, ten times as much as the other 97 percent put together.
Edit: I had often heard of this study and just pasted the first reference I found. I would delete this post, if I could, as its credibility is questionable. Thanks femto.