Any athletics coach can tell you about positive visualization. Before a race, imagine yourself beating your best time and inching out your competition, and it will help you during the race. Positive visualization may work in sports, but it does not work in sexual relations.
Often, I will positively envision myself hooking up with a hot girl. I may even drive myself to exhaustion after positively visualizing a particular girl multiple times a day. But it doesn't help. I've found no correlation between positively envisioning sex, and actually getting sex.
Rarely do I actually hook up with girls whom I imagine myself hooking up with beforehand. Positive visualization is a crock of shit.