humbleness

Keep in mind that being humble has many benefits. Humility can help you be more content with your life, and it can also help you endure bad times and improve your relationships with others. It's also essential to being an effective learner. If you think you know it all, you won't be open-minded enough to seek out new knowledge. Humility is also, somewhat counter-intuitively, an excellent tool for self-development in general. After all, if you feel superior, you have no incentive to improve. Most of all, being humble allows you to be honest with yourself.
Seek trusted and wise counsel and obtain accountability partners if you find this to be a weakness in your life. Pride comes before the fall and prevention is definately better than cure.

[edit] Warnings
Pretending to be humble isn't the same as being humble, and often people who pretend to be humble do it in order to seek out praise. Other people will recognize this, and even if you fool some, you won't derive the same benefits as you would through actually developing humility.
Similarly, don't confuse being humble with being sycophantic (being overly-praiseful of someone for your own profit). This is a common misconception, but the two attitudes are completely different.
Now that you know that humility wins, don't use it as a manipulation tactic. Many people pretend to be humble, but are in fact not. There are many 'wolves in sheep's clothing' out there. Use discernment with all people.