A few years ago I was standing on the roof of my house (the loft was being converted - it's not something I normally do). I spotted a bird of prey (a hawk I think) circling overhead. Rabbits lived in the field opposite and I wondered if I the hawk would swoop on one - something I'd never seen before. And with that the hawk began to dive! It was clearly targeting a young rabbit sitting by the far hedge... The rabbit sensed the danger, stopped eating, and started running for its life... The hawk changed direction and kept after the speeding youngster... got very close... reached out with its talons... was about to make its kill.... And at that exact moment the rabbit changed direction. I don't mean it veered off slightly to the left or slightly to the right. I mean one moment it was running as fast as it could along the hedge and the next moment, with almost no discernible pause or reduction in speed, it was running in the opposite direction back to where it had came from. It was quite something. The rabbit was certainly fast but the hawk was faster. What saved the rabbit was its nimbleness. It's agility.
Agility isn't how fast you can keep going in the same direction; agility is how easily you can change direction.