Everyone has at least two sides to their personality. The light side that gives. This is the generous side, the funny side, the happy side, the assertive side, the side that makes people want to be around you because you are helping to fill (yang) their needs.
And then you have the dark side, the side that takes. The side that withdraws from people, that doubts, that restrains from giving or doing. The cautious side, the worried side, the afraid side. The side that is waiting for the world to help you fill your needs (yin).
Contrary to popular belief, it's not a matter of getting rid of our yin side. Of simply being more generous, more social, more assertive, more audacious. It's a matter of balancing our yang with our yin, of filling our dark side with light.
For example, let's say you want to get a raise at work, but you are too afraid to ask. Or you're worried that you aren't worth the raise. Instead of fighting with yourself about it ("Am I worth it or not?") , ask yourself: "What information or standard do I need in order to know that I deserve a raise?"
One standard could be if you have contributed more money to your company than your worth. If your annual salary is $50,000 and you've helped the company gain $100,000 worth of sales, then it's reasonable to assume you're worth a raise.
Another standard could be if you have improved systems and processes at work. If you've significantly cut the number of man-hours required to do a specific task, then you've saved your company a lot of money. It's reasonable to assume, then, that you are an asset to the company and deserve a higher raise.
Most people assume that they must fight or destroy the doubt, fear, anxiety they feel in life. But your yin side is as much an integral part of you as your yang side, even if it's unpleasant. It tells you where you need to create balance and happiness.
The solution, then, is not to fight with yourself, but to find peace in yourself. Shine some light into your darkness.