If two people go on a walk together, one person has to adjust to the speed of the other, either speeding up or slowing down (rarely do both adjust speeds).

Metaphorically, it's a simple principle: in every situation, one person adjusts to the pace set by the other. This basically explains the entire concept leadership, and can extend to groups of people.

If your aim is to lead, you must set the pace and enforce it. This is rarely done verbally -- your actions set the tone and compel others to follow suit. Without consciously thinking about it, people will adjust to your pace if you're consistent and steadfast in setting it.

(It doesn't hurt to actually be good at what you're doing too. Otherwise no one will be paying attention to you anyway. )

Just like on a walk, it often happens without anyone even noticing. Leadership isn't about a title or ceremony or speech. You don't make people do it. You don't motivate someone to walk faster (and if you do it won't last -- you'll have to do so again and again). It gradually happens when someone sets the tone and maintains the pace... And you look up and see others following.

Just start walking.