Home exercise: get your dog lying in sphinx position on a surface with good traction.
Next, scratch his belly to get him into sitting position whilst getting him to stay facing forward & straight.
Next, scratch the base of his paws above the pads to initiate his reflex to push up. Once he is standing, maintain this position for 5 seconds before allowing him to return back down to a square sit position.
On the last rep, maintain the standing position for 10 seconds.
If your dog struggles to sit fully, pillows or a platform to create a “half sit”