In the 20th century, leaders identified goals for their organisation, described the jobs required to meet those goals, and hired people with the right skills to fill those job descriptions. Over time, people build on their skills and move into different roles, climbing a well-designed career ladder until retirement. That's no longer the case. Our world is changing so fast that neither goals nor roles are clear and well-defined. The skills you need for the future aren't the same as the skills you have now, and the best people have multiple careers (not even just multiple jobs) over their working life.