When Socrates was asked why he was considered the wisest man in Greece, he replied, "It is because I know that I know nothing."
In the seventeenth century, Isaac Newton, who discovered the Law of Gravitation and was one of the greatest scientific thinkers, made a very humble statement about his discoveries. He said he felt like a child playing with pretty shells of knowledge by the seashore, while the great undiscovered sea of knowledge stretched alluringly beyond him.
This kind of intellectual humility, however, is different from the kind of inferiority feeling that makes you feel stupid in comparison with your next door neighbor or your immediate superior at the office. Most likely, he is superior merely in position, and possibly in acquired knowledge. What he has done, you can do. Often it is mostly a matter of believing in yourself, and letting that belief help you with anything you attempt.
In the long run, you will be happier and get further if you have real faith in yourself, and are neither too humble nor too proud.
An inferiority complex is like a fungus that absorbs healthy living matter. Don't let it sponge away your great, dynamic personality! It takes a lot of courage to build up the self-confidence that the years have corroded. You have that courage!