We are several decades into the "believe it, achieve it" delusion in the business world. Several decades before that I was raised on a little engine that could, by personal willpower alone. "I think I can, I think I can..." therefore, I will.
It makes for great movies, for mythic success stories, but for some it becomes an anesthetic to the realities of life. I once worked with a sales person who started each day with a different motivational saying. She talked herself into joy and optimism every single day. Trouble was, she spent the rest of the day repeating the mantra de jour, but doing nothing else about it. Before long she was broke and unemployed, still, presumably with that optimism of certain wealth just around her cheery corner. She's one of many.
There's a business lesson in all of this, that optimism and self-motivation alone are not enough. Hard work, continuous growth, reflection, the good sense to ask for help, properly directed sweat equity AND a great attitude are all predictors, but not guarantors of success. Pithy quotes? A little, but not so much.
You think you can? Just do it.