The following article is from Brian Tracy
The worst beliefs you can have are “self-limiting beliefs.” These exist whenever you believe yourself to be limited in some way. For example, you may think yourself to be less talented or capable than others. You may think that others are superior to you in some way. You may have fallen into the common trap of selling yourself short and settling for far less than you are truly capable of.
These self-limiting beliefs act like brakes on your potential. They hold you back. They generate the two greatest enemies of personal success—doubt and fear. They paralyze you and cause you to hesitate to take the intelligent risks that are necessary for you to fulfill your true potential.
For you to progress, to move onward and upward in your life and your business, you must continually challenge your self-limiting beliefs. You must reject any thought or suggestion that you are limited in any way. You must accept as a basic principle that you are a “no-limit” person, and that what others have done, you can do as well.
When I was a young man, coming from a difficult upbringing, I fell into the mental trap of concluding that because other people were doing better than I was, they must be better or smarter than I was. I accidentally concluded that they were worth more than I was. I must therefore be worth less. This false belief held me back for years.
The fact is that no one is better than you are and no one is smarter than you are. If they are doing better, it is largely because they have developed their natural talents and abilities more than you have. They have learned the laws of cause and effect that apply to their lives and work before you have. And anything anyone else has done, within reason, you can probably do as well. You just need to learn how.