To develop health, longevity and ultimately, immortality, seated meditation is the key practice.
Sit, either in a chair or better, cross legged with the hips comfortably supported. The spine should be straight and unsupported. Place the hands on the knees with the thumbs folded in the palms and the fingers wrapped around the thumbs. Place the tip of the tongue on the roof of the mouth just behind the teeth. Lower your eyelids, women may close the eyes, men keep a slip of light showing through, and focus the eyes towards the tip of the nose. Turn the internal gaze gently to the Dan Tian in the center of the belly. As you inhale gently contract the belly, as you exhale, allow the belly to gently expand. See and not see. Withdraw the senses from the external world and simply be an observer, a companion to the Dan Tian.
From stillness comes motion. With time a sensation will arise in the Dan Tian as the Qi begins to move. Remain the observer, do not engage the mind, the awareness, or the emotions and allow the Qi to move naturally.
With stillness internal transformations begin to manifest. The three treasures of the Tao: Jing, Qi and Shen are cultivated. In the first stage Jing is built up until it is mature and Jing transmutes to Qi, then, when the Qi is mature, it transmutes to Shen, then Shen returns to the Void and the Void to the Tao. With each stage of internal transmutation, external changes manifest as well as the body first heals itself, rejuvenates and finally becomes immortal.