Can someone really completely change their personality?

I found this on a website and after reading it I thought it was useful for me so Im gona share the passage below with you all today..

"Being shy usually comes with being passive or being indecisive. If you are passive, your shyness will allow others to take advantage of you for being so bashful. Passiveness and indecision will only lead to a life of discomfort. If your shyness gets to the point that you start sweating for the slightest things then you should start doing something about it."

"If you have a shy personality there's no need to force yourself to be someone you're not but if it's interfering with your well being or success you can find ways to change things. First of all make sure to express your feelings and thoughts clearly to others. There's no good reason to fear being yourself. Talk to complete strangers a few times a week and practice being social even if you're fluttered at first. Eventually you'll come out of your shell. Understand that you can only be yourself. Know what you want and try to make up your mind quicker but stay very precautious."

Shyness can be something that you have complete control over if you know how to take care of yourself and find courage in the truth.

"Self-confidence is a state of mind that comes through actions. You can become more confident by becoming a person with a purpose. Find your passion and confidence will soon follow. Learning the most You can about Your interests will also give you the confidence to live your life with Pride. Never confuse confidence with naive arrogance. True Confidence will come to Good people."

Taken from: http://advice7.com/emotions_feelings/shyness.html

I can only be myself so there's no point forcing myself to change my personality.. But There's things I can do to make situations in future less uncomfortable, and easier to deal with.. My shyness is killing me... Iam not happy about it and im sick of it.. If I cant even sing at the front of the class to my friends and be cool about it, then how the hell am I ever gona cope with tallking to an audience and being on TV? I still want to go back to HK and be a professional singer... I need to sort myself out... NOW!!!