In HBO's new documentary, "Becoming Warren Buffett," the investing legend says there were "two turning points" in his life: "One when I came out of the womb and one when I met Susie."
"What happened with me would not have happened without her," he says of his first wife, who died in 2004.
In fact, the third richest man in the world says the biggest decision of your life will be who you choose to marry.
"You want to associate with people who are the kind of person you'd like to be. You'll move in that direction," Buffett said in a recent conversation with Bill Gates at Columbia University.
"And the most important person by far in that respect is your spouse. I can't overemphasize how important that is."
Facebook COO Sheryl Sandberg, whose estimated net worth is $1.3 billion, has a similar perspective.
"I truly believe that the single most important career decision that a woman makes is whether she will have a life partner and who that partner is," she writes in her bestseller "Lean In."
"I don't know of one woman in a leadership position whose life partner is not fully - and I mean fully - supportive of her career."
Buffett and Sandberg's claims are backed by research.
One study, by Brittany C. Solomon and Joshua J. Jackson of Washington University in St. Louis, shows that having a conscientious spouse can boost your salary significantly.
"With every one-standard-deviation increase in a spouse's conscientiousness, an individual is likely to earn approximately $4,000 more per year," the Harvard Business Review reports.
Additionally, "employees with extremely conscientious spouses (two standard deviations above the mean) are 50 per cent more likely to get promoted than those with extremely unconscientious spouses (two standard deviations below the mean)."
Conscientious spouses tend to handle a lot of household tasks, allowing their partner to focus more on their career.
Plus, people tend to mirror their conscientious spouses' diligent habits, the research team finds.
After all, as motivational speaker Jim Rohn famously said, "You are the average of the five people you spend the most time with."