Through my life and my experience, I believe getting "positive mental attitude" is true. Your brain has certain pathways in it, and if you feed those pathways with certain types of thoughts, the blood goes to those neurons and nourishes them, and they grow and develop. That's how you build habits. Physically, I think that's how your brain works. If you have certain habits that are negative and causing you problems that you want to change them, you can actually change the blood flow and stuff in your brain by thinking a different way.