No matter what gait your horse is in, maintain forward momentum.
When we talk about developing and training horses we have to remember that the desire to go forward must be greater than anything else. This desire to move forward into the bit will give us the contact required to achieve the roundness and thoroughness, as well as the uphill tendency that we can appreciate in the picture.
It is very important to work on achieving suppleness, thoroughness, and impulsion from the early stages of the training. Only following the training scale will we be able to achieve true collection later on.
Very often we see horses that are very spectacular but are not moving through the back. This movement, usually achieved through tension, will lead to problems later on and often injury, and it is heavily penalized at an international level.