I have friends who've had the good fortune to have met and in some cases work alongside Nelson Mandela. Invariably, they talk about his great natural charm, his ability to focus on whomever he was speaking with, so that they felt dignified by his attention.

This was no mere affectation. It sprang in part from his drive to learn from others. No matter who he was in conversation with, Mandela believed he might learn something.

The other factor at work was his iron will. Throughout his imprisonment - where he was as much a leader as during his presidency - Mandela maintained a stubborn belief in the rightness of his cause. This gave him the courage to stand on the inside, within his psyche, when he was under tremendous pressure to bow on the outside.

In an age of bullying leadership, where throwing tantrums is often confused with forceful personality, we must learn this skill of quiet, yet stubborn determination.

And we must learn to wrap our personal focus in a respectful and genuinely curious attitude toward others.

Your Impact is More Important than Your Image.

In this age of ubiquitous celebrity, much is made of people who have 'star quality' and leaders who possess unusual charisma.

The finest leaders in history, though, haven't always been the type of people who light up every room they enter. Often, they've been people who leave left a strong echo when they depart.

Nelson Mandela was keenly aware of his celebrity power. Yet he used this as a currency to purchase better conditions for his people and more international investment for his nation.

For him, any celebrity or image that was attached to his leadership served merely as a means to a much more important end.

Many a leader faces the temptation to make decisions in the interests of short-term perception rather than longer-term corporate or social benefits. For some, the highest goal is the flattering profile in a glossy magazine, or being invited to sit at the best table in an industry or political conference.

This approach will not survive long in the emerging market or among the emerging generation.

As the spread of social networking and other digital technologies brings a greater level of transparency to leadership, individual leaders will increasingly be judged more on performance than personality. And those who treat their leadership position as nothing more than another step on the career ladder will be found wanting.

Today, leadership in any sphere must be seen more as a vocation.