T. Boone Pickens, legendary oilman, business tycoon, and philanthropist, died September 11 from natural causes at his Dallas home, a spokesman for his foundation announced.

Born in Holdenville, Oklahoma, on May 22, 1928, Pickens knew hard work from an early start. At age 12, he had his first job as a paperboy.

"I always had money after that, in my pocket, and it was a good feeling," he told CNBC.

Pickens graduated from Oklahoma State University with a degree in geology, then began his career at Phillips Petroleum. Later, he founded oil and gas company Mesa Petroleum, taking it public in the 1960s and realizing the power that comes with being a shareholder. Pickens helped revolutionize how corporate executives are paid, advocating for compensation to include shares.

His move from geology to corporate finance was solidified during the 1990s, when he founded energy hedge fund BP Capital, which made him a billionaire. During his life, Pickens donated $1 billion to charity, half of which went to his alma mater. He would also use his voice to advocate for energy independence and clean energy.

Much of Pickens' fortune went into his beloved 65,000-acre ranch in the Texas Panhandle. He put the masterpiece on the market for $250 million in 2017.

Pickens’ business experience and outspoken nature made him the perfect TV regular in his later years, offering his colorful insight on the state of the energy industry. He even developed “Boone-isms,” pithy sayings and prognostications that helped build his fandom.

The Dallas Morning Newsmade a list, including:

• “Don’t fall victim to what I call the ‘ready-aim-aim-aim-aim’ syndrome. You must be willing to fire.”
• "Show up early. Work hard. Stay late. Work eight hours and sleep eight hours, and make sure they are not the same eight hours."
• "My mother once told me, 'Son, you talk too much. You should listen more. You don't even know who the enemy is.'"
• “If you’re on the right side of the issue, just keep driving until you hear glass breaking. Don’t quit.”
• "Play by the rules. It's no fun if you cheat."

Throughout his life, Pickens had five marriages, including to Toni Brinker, the widow of Dallas businessman Norm Brinker. They divorced in 2017.

Pickens is survived by five children, 11 grandchildren, and "an increasing number of great grandchildren," according to the foundation. He's preceded in death by one grandson, Thomas "Ty" Boone Pickens IV, who died from a drug overdose while a student at TCU in 2013.