I think that there are two very important reasons why people get promoted. The first reason is that they have good career plans in the beginning of their career. We always meet some young people who look very mature and steady and very different from their peers. They might have been taught how to understand the rules of reality at an early age and did their best to learn essential skills after they started their career. On the other hand, most students just focus on their academic achievements until they graduate from university, only then they begin to learn how to survive competition with their work colleagues. I even saw some people who didn't know how to keep a good relationship with others, let alone how to get promoted. Additionally, I think that good opportunities are the key to getting promoted. For example, meeting a kind superior/manager/employer who can help you improve your skills. No matter which reason is the most important, being stronger is the essential prerequisite to get promoted. Indolence is your biggest enemy, so please remember that no pain, no gain!