Look where you want to ride, not at the neck: shoulders, pelvis and weight follow your eyes automatically — your seat corrects itself without you doing a thing.
Of all the seat corrections, this is the only one that works instantly and without thinking. The reason is mechanical: turn your head and your shoulders and pelvis follow, and with them the weight aid your horse actually feels. Stare at the neck or your own hands instead and your torso tips forward, loading the forehand — then you wonder why the turn falls apart. In the arena that means looking one letter ahead, not at the marker you're on. Over a fence it means fixing your eyes on what comes next before take-off. One detail people miss: mountaineers use the same mechanism on exposed ground — looking at your next foothold keeps you steady, looking into the drop does not. In the saddle it stays the other way round: your eyes go forward onto the line, never down.