Realize that your physical experience and environment is the materialization of your beliefs. If you find great exuberance, health, effective work, abundance, smiles on the faces of those who you meet, then take it for granted that your beliefs are beneficial. If you see a world that is good, people like you, take it for granted again, that your beliefs are beneficial. But if you find poor health, a lack of meaningful work, a lack of abundance, a world of sorrow and evil, then assume your beliefs are faulty and begin examining them.