From Seth Godin (of whom I'm generally a fan):
The thing is: clear visualization, repeated again and again, doesn't actually decrease the chances you're going to fail. In fact, it probably increases the odds.Apparently not. I first read this in Made to Stick (Amazon) but I found a reference online that details the study fairly well at Officer.com.
When you choose to visualize the path that works, you're more likely to shore it up and create an environment where it can take place.
Rehearsing failure is simply a bad habit, not a productive use of your time.
Basically, a study from UCLA showed that simulating past events (thinking about past problems step by step, going through them in detail, the actions you took, what you said/did, the environment) was much more helpful than simulating future outcomes. Those who simulated past events experienced better moods almost right away and were likely to have taken specific action to solve their problems.
The authors of Made to Stick, Chip and Dan Heath possibly facetiously suggest that counterintuitive to pop psych literature urging you to visualize success, maybe instead of visualizing that we're filthy rich, we should be replaying steps that led to our being poor.