Motivation is literally the desire to do things. So figure out what you want, and start being who you want to be.
No one, including yourself, can make you feel bad or less than you really are, without your permission.
Having pride in yourself, what you do, and how you do it is the underlying fuel for motivation. Learning to give one hundred percent in your practice will slowly establish pride in your Kung Fu. As your pride grows due to your hard work in your practice, your motivation will also grow. As a result, this motivation will start to flow into other areas of your life.