Ask your dog to sit (or down)
Use your GOOD REWARD MARKER and reward your dog in position (don't allow
them to break position to get the food).
After several seconds, use your TERMINAL MARKER or RELEASE WORD to release
your dog from the position.
Try again and add a few seconds between rewards (don't continually add on to the
duration, ping pong with the time, eg. 2 seconds, 4 seconds, 3 seconds, 5 seconds)

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If your dog breaks position before you release...
Use your NO REWARD MARKER and guide your dog back in to sit.
Always reward for small successes, and try to release your dog before you think they
will break position.