A knight on a white horse charges at full gallop, sword raised high. The horse's front legs reach forward, the clouds are torn, the trees are bent by wind. There is no hesitation anywhere in the picture. The card describes a person, or a way of acting, that pushes straight ahead once the mind is made up.
At work this is the one who decides fast and moves. When a meeting drags on, they say 'let's go with this' and wrap it up; when they spot a problem, it is fixed by end of day. On a team that already has enough to decide on and keeps testing every stone, this person gets things rolling. When the words speed up too, though, they tend to come out sharp.
Reversed, the brakes are gone. Pushing to win, speech and actions get rough and nobody notices who got hurt along the way. The other direction is speed with no heading — always moving, never sure where to.
What the card asks you to check is whether you are rushing because the decision is made, or because you want the discomfort over with. If it is the first, go. If it is the second, the faster you go the more you will have to come back and redo.
It is often praised as 'brave' or dismissed as 'reckless'. The knight's speed is neutral in itself. Pointed the right way it is momentum; pointed the wrong way it is a crash. That is why this card is always read together with where it is heading.
With the Chariot the goal is clear and the force is there, so this really is a place to speed up. With the Four of Swords the signals collide: the urge to charge against a body that needs rest, and stopping first is usually the right call.