Early in his career, a 20-year-old Buffet was terrified of public speaking. To force himself to face his fears, he signed up for a public speaking course with the Dale Carnegie institute.
After graduating from the course, Buffett went to the University of Omaha and, to fully overcome the phobia, asked to teach a class, recounts Tim Ferriss in his book about the habits and processes of successful people, "Tools of Titans."
Even in the face of his greatest fear, Buffett didn't let anything hold him back. Instead, he faced it head on, something he'd have to continue to do as he built up Berkshire Hathaway and became a visionary to his thousands of employees and fans.
Robbins tells Ferriss he has heard Buffett say that "investing in yourself is the most important investment you'll ever make in your life."
Robbins also attributes his greatest investment to a class: When he was 17 and earning $40 a week, he spent $35 for a three-hour seminar with personal development coach Jim Rohn.