When your horse in on the brink of a precipice, it is too late to pull the reins

We're having to pull back the reins.

He's always pumped up. Sometimes, you have to pull the reins in.

You think you lost your horse? Who knows, he may bring a whole herd back to you someday.

When you bow, bow low

Of all the stratagems, to know when to quit is the best