To ride this exercise you trot down the 3/4 line.
Once you are confident you are straight, ask your horse to leg-yield back out to the track, using your inside leg to ask for the movement and your outside aids to stop him from falling out.
When you reach the track, do a stride or two where you are straight, before leg yielding back to the 3/4 line.
You may find that your horse is more resistant to leaving the track than he is to leaving the 3/4 line in leg yield, so make sure you are clear with your aids.
Keep the angle of your leg yield shallow at first but as you become more proficient you will be able to fit in more zigzags along the long side.
Once you are confident travelling between the 3/4 line and the track, try travelling between the centre line and the 3/4 line. This is much more difficult as you don’t have the edge of the arena to support you.