Good morning. Fortune Editor-in-Chief Alyson Shontell writing this morning from New York. If you’ve heard of Bill Ackman, you probably have an opinion of Bill Ackman.

The outspoken billionaire is the founder of Pershing Square, a hedge fund that has made wildly successful bets (like Chipotle and Canadian Pacific Railway) and overcome epic disasters (like Valeant Pharmaceuticals and Herbalife).

When I was researching Ackman for the latest episode of my Fortune 500: Titans and Disruptors of Industry podcast, I was struck by qualities he expressed when he was young that would later shape his career.

One was his ambition. As a teenager, Ackman predicted to his dad (who gave him no allowance and declared he would never receive an inheritance) that he would become a millionaire by age 30, have $100 million by age 40, and become a billionaire by age 50. Ackman wound up hitting each of those milestones ahead of schedule.

When he started his first firm, Gotham, out of Harvard, Ackman secured financing by cold-calling moguls on the Forbes 400 list, a ranking of the wealthiest Americans. “I figured if I want to raise $10 million, why not go to the richest people in the world and ask them for a relatively small amount of money?” he told me. A few said yes.