Attach dual handles to a sled connected by a rope or chain. Load the sled to an appropriate weight. Face the sled, backing up until there is some tension in the line.
With a handle in each hand, bend the knees slightly, keep your head and chest up, and begin with your arms extended.
To initiate the movement, flex the elbow as you retract your shoulder blades, pulling the sled towards you.
Take a step or two back to get tension in the line and repeat.