The power of beliefs in humans lies on the fact that the former can be the cause and the outcome at the same time of learned helplessness. Not only the external stimuli, but also the unique way that individuals interpret things around them, can cause a state of learned discouragement. So do question your beliefs. It is not as simple as to just command it, (actually that would not be completely of no use); however, there are some effective ways for disputing our beliefs.
1. Expose yourself into numerous and different environments. That will give an alternative perspective.
2. Keep yourself in a general good physical and mental condition. Our condition can bias and distort our beliefs.
3. Spend some time of the day to sum up, refine and in fact question the input of the day.
4. Discuss a lot, search and ask questions on any situation you face. That is probably the most effective way to dispute a belief.
5. Relax, have fun and enjoy life. The more we enjoy every minute we live, the more our natural-primary psychic material comes out and contrasts the beliefs we actually have learned.