I don't mean to be blunt, but you don't.
I agree... although I do believe most players need to know how to use a change of pace a lot better than they do. Hingis did this brilliantly and used a slow, topspin shot at the right moments to get opponents back behind the baseline and would often drive the reply into the open court or if the opponent tried to "moonball" back she would take it out of the air. Few players at the moment have the presence of mind to use this tactic, or they use it at the wrong time. Caroline Wozniacki likes to mix the pace but sometimes she drops it way short in doing so - has to be deep.










