Now a judge on ABC's "Shark Tank" and owner of the Dallas Mavericks, Mark Cuban became a billionaire back in 1998 when he and Todd Wagner took their online audio streaming company, Broadcast.com, public.
But Cuban had been a millionaire long before he entered the three-comma club. And he credits the drive to earn his first million to a book he read when he was just starting out: "Cashing in on the American Dream: How to Retire at 35" by Paul Terhorst, as he told Money in a recent interview.
The book centers on the idea of focusing on your priorities and living well below your means. It encourages readers to downsize their houses, cars and other expenses, and spend time developing their passions and finding meaning in their lives beyond work.