To feel the benefits of yoga, you really have to make it a regular practice. Like anything in life, you reap what you sow. And the more you put into your yoga practices, the more you feel the benefits. You can't expect to harness inner calm and peace, without working on it.
You can't expect your shoulders to release from up around your ears, without consciously and repeatedly letting them slide down your back. It is when you have worked hard, and put the practice into your body, that doing yoga feels so good.
At first coming into these shapes, moving with our breath as the guide, and taking a more internal approach, feels awkward and uncomfortable. As our bodies adjust and our perception shifts, we begin to feel comfortable and confident practicing and the benefits start pouring into our lives.
Suddenly, the old ways we had of carrying ourselves give way to the new habits we've created in our bodies and we see changes, physically and mentally.
So basically what I'm saying is: don't get discouraged and keep practicing. Repetition allows the magic to rise.