First, do the thing others have asked you to do. Then, figure out how to do it faster and more efficient. Finally, find better things to work on.
Wondering why you haven't received that promotion? It's probably because you haven't given yourself one, yet.
Working on things that others have assigned you to work on is good. It's how you learn. It's how you gain experience and make yourself valuable. But there comes a time when you must choose yourself. Give yourself a promotion by learning new skills, trying different things, innovating, and creating a more useful contribution.
The kind of promotion you are really looking for won't come from others. And it certainly won't come tomorrow unless you invest in the proper things today.