Early on, Nike's billionaire co-founder Phil Knight had people telling him he wouldn't make it.
Yet, despite the haters, he still steered Nike to become the world's No. 1 athletic-shoe company, with a brand so powerful it can be recognized by a checkmark.
Knight recently chronicled his journey of turning Nike into a $91 billion company in his memoir, "Shoe Dog." In an interview with CNBC's Jim Cramer on Thursday, Knight said that many doubted his ability to succeed.
"I've had a lot of people tell me, 'We ... think he's not going to make it,'" Knight said.
He always knew he could fail, but his optimistic outlook helped him persevere, he said. Building Nike was the most fun he ever had. His team had a cause, and they believed they would succeed.
Any adversity that was thrown at them, they knew they could overcome.
"We knew we could fail, we just didn't think we would," Knight said. "We loved doing what we were doing, and we loved each other."