Become your own cheerleader. Take some time to look back and appreciate your accomplishments. We tend to remember only the bad moments and give too much importance to our failures. Begin respecting and taking incredible care of yourself, and show others how you should be treated. If you still have problems praising yourself, consider writing a success diary to keep your spirits high.
As you begin to experience the pleasure of discovering that you are stronger than you thought, you will feel more motivated to say loud and clear what you want, thereby getting others to respect the rules that govern your personal world.