While Martin Seligman didn't make it on my list in my comment. I read him as well and IMO he's completely legit as a psychologist (way more legit than I am, and

While Martin Seligman didn't make it on my list in my comment. I read him as well and IMO he's completely legit as a psychologist (way more legit than I am, and I even published a paper on the neuroscience/psychology of gamer frustration and engagement). He has studied the concept of learned helplessness (a fascinating concept) and optimism itself. Simply following his advice will make anyone's life more awesome.