A student asked a great question: Why does neidan focus on capturing the true yang and not the true yin? (My initial reflection was: No, this can't be due to cultural bias, or can it?)
Jing, qi, shen are called the three treasures of life. In qigong there is not the idea of subduing the flesh in service of the spirit. In fact, the spirit depends on the flesh. So cultivation is the strengthening and refining of all three but at different stages of the practice more emphasis is put on one than another. 
We talk about jing>qi>shen. Its more complete to talk about zhuji>jing>qi>shen. Zhuji means building the foundation and is the first stage. Zhuji means restoring and strengthening the three treasures. When they are full and rich, the body mind spirit is prepared to launch into cultivation and refining. Without that it's going to be very difficult. So zhuji puts the biggest emphasis on the body, the yin. When you feel good after qigong practice you are feeling the effects of zhuji - the three treasures are fuller and more harmonized: the body is stronger, you feel more comfortable in the world, the mind is clear and calm. When we talk about capturing the true yang we are talking about an advanced stage of practice: spirit>emptiness. The emphasis is on the yang of spirit and beyond, not on the yin of embodiment.