Some horse's conformation inhibits them from being able to collect easily and hold it there. Arabians, though, usually have no issue doing it because of their conformation. In this instance, it would be a training issue. To get the right headset and collection, your horse first has to learn to be soft in his face. By that, I mean he should flex at his poll and give his mouth to you when you apply pressure on the reins. To add collection to the picture, when you pick up on the reins apply leg pressure as well to tell him to be soft in his face and not to speed up, but to lift up his back and engage from behind.
Opportunity is missed by most people because it is dressed in overalls and looks like work. ~Thomas Edison