Exercise: Ride EVERY stride of a line straightly.
Apply: Pick an EXACT distance to stay off the track and ride your warmup on that inside track. At any moment, you should be able to measure your hoof marks and find that they are within inches of that selected distance. Remember to follow the selected line through your horse's ears.
Continue to do the same on perfect 20-meter circles and diagonals. Remember to focus on the imaginary dotted line from each point, through your horse's ears.
Confirm that you know how to ride the points of the following:
20-meter circle in the center: Hit at E, 2 meters before I on the centerline, B, 2 meters before L on the centerline.
20-meter circle on the ends: Hit at C/A, 4 meters after M/H/K/F on the track, 2 meters past I/L on the centerline.
Diagonals: HXF, KXM