The obvious fantasy personified by Pistorius is of the underdog overcoming overwhelming adversity to achieve triumph. A man without legs reaches the semi-finals of the 400-meter track event at the Olympics? "If that can happen," one can just hear parents around the world telling their children, "then you can do anything." Even if you're not perfect. Or you have some physical defect. Or you're sick.

It's a powerful and uplifting message that we want to believe, in all its simplicity and potential for a happy ending. Fade to credits, everyone leaves inspired.

Unfortunately, the equation of achievement is far more complex.

In a revealing profile of Michael Jordan at 50, published this week on ESPN.com, Wright Thompson writes that the young Jordan believed his father preferred his older brother, and spent a lifetime driven to achieve as a way of proving his worth. "This appetite to prove—to attack and to dominate and to win," Thompson notes, "... has been successful and spectacularly unhealthy."

Even Jordan acknowledged that his self-esteem has always been "tied directly to the game." Hence the drive, the rage, the relentless pursuit of victory that led to astounding feats of skill and six championship rings in his dresser drawer. But Jordan also talked to Thompson about what the process of that pursuit does to a person. "You ask for these special powers to achieve these heights, and now you got it and you want to give it back, but you can't. ... I drove myself so much that I'm still living with some of those drives. ... I don't know how to get rid of it."

It's an aspect to achievement that we often shove aside in our focus on the shining moments of record-breaking triumph. And that goes for more than just sporting feats and icons. A friend of mine, whose job gave him access to many of the top CEOs in America, told a similar tale about their motivations and demons. I'd kidded him, back in my single days, to keep me in mind if he knew an interesting CEO who was single and age-appropriate.

"I do," he answered. "But the truth is, I wouldn't wish any of them on you."

"Why?" I asked.

"Because they're generally not easy on their wives or families," he answered. He went on to explain that he'd developed a theory about top-achieving CEOs. "Almost to a person, they've been denied something that really mattered to them, early in their lives. So they spend the rest of their lives making up for it. Achieving. And not only does that make them pretty focused on themselves, it also means that no achievement is ever enough. They're driven."

That, mind you, is before you throw in the ego that develops with success or the impact that sudden wealth, power, and fame can have on people who are ill-prepared to cope with it. You spend years laser-focused on yourself and your own achievement. And then, if you're successful, suddenly everyone else is focused on you, as well. As Thompson noted, "[Jordan] is used to being the most important person in every room he enters and, going a step further, in the lives of everyone he meets." Those in Jordan's life, Thompson says, are well versed in not only his achievements, but also "his ego, his moods, and his anger."