Shiva as a Yogi...

Yoga is the cessation of mental activity.

The task of yoga is to destroy vasanas without producing new ones.
Vasanas are (by definition): impregnation; the residiual trace left by an act or thought; cause of the metaphysical ignorance that produces alienation.
A metaphor can be used to describe this easily. Just as a piece of cloth retains the scent of a flower that had lain upon it for a moment, so do people retain impressions from all actions and thoughts, such as meeting people, or seeing something, or being somewhere. The Yoga Sutras are the texts, written by Patanjali, which detail yoga and divide the path leading to liberation into eight stages.

1. yama=restraint
2. niyama=spiritual discipline
3. asana=posture
4. pranayama=breath control
5. pratyahara=withdrawl of the senses
6. dhrana=mental concentration
7. dhyana=deep meditation
8. samadhi=higher concentration

1.yama

The yamas, or restraints, are five in number: 1.do not harm living beings, 2. do not lie, 3. do not steal, 4. abstain from sexual relations, 5. eschew covetousness. These may sound hauntingly like the Ten Commandments. However, to follow these restraints is not merely to restrain from taking part in them, as the translation indicates, but rather to erase all desire to do these things from your mind. As you practice yoga in full, the desire to do these things will be wiped out naturally, when you see how pointless these things are. Therefore, the point is not to detain yourself unwillingly, but rather to let these desires pass away without notice.

2.niyama

The niyamas are practiced simultaneously with the yamas and are also five in number: 1. to be clean, 2. to retain equanimity in all circumstances, 3. to practice asceticism, 4. to study, 5. to be devout. The cleanliness refers not only to physical purity, but also purity of mind. A novice is urged to wash his mind. Asceticism is going beyond the contraries that characterize existence, such as hunger and thirst, hot and cold, the desire to stand and the desire to sit, etc. For example, in India one does not drink with meals. You must therefore decide which is more immediate, your hunger or thirst. Ascetic virtue is then mastering one's desires to trascend the preference that would arrive from such a decision. However, studying and being devout also carry with them some dangers. If one becomes too eager to study and to practice, it becomes a desire, even if that which is being studied is teaching loss of desire. Desires accumulate vasanas and karma, the elimination of which is the sole purpose of yoga.

After a novice has mastered these first two degrees of yoga, at the master's decision, the master confers initiation on him. The master adopts the novice, gives him a mantra, which the repetition of will eventually be his "recipe" for enlightenment. The disciple receives a new name, and the mantra is whispered secretly into his ear. It is rumored that some disciples become instantaneously enlightened upon hearing the mantra

3.asana

Asanas are postures or ways of sitting and these are learned simultaneously with with pranayama, the following stage, which is breath control. In both cases it is a question of attaining mastery over the body, whose intrinsic harmony--unfortunately veiled in the average man--will then be revealed. Patanjali defines what this posture should be in two words: firm and relaxed. He feels no necessity to say more than that; primarily because the postures cannot be learned from written texts, but also because the two adjectives sufficiently convey the fact that any position at all is suitable for the practice of yoga, provided it can be held for a long time without discomfort...as soon as one is capable of taking up one's prefered asana instinctively without thinking about it then one has successfully completed the third stage of classical yoga. The lotus, the position most frequently employed by Indian yogis, consists, according to the Yoga-Kundalini Upanishad, in

sitting cross-legged,
with the soles of the feet upward
resting on the two thighs;
right foot on left thigh;
left foot on right thigh;
this position, called "the lotus,"
is a remedy for every sickness.

4.pranayama

In India, ordinary breathing is conceived of as a threefold process. It consists of inhalation, a pause, then exhalation. Moreover emphasis is placed on the fact that in individual-in-the-world, because he is subject to the laws of existence, is incapable of maintaining a stable respiratory rhythm: at certain times the rate speeds up or slows down as a result of circumstances external to the breathing itself (running, anxiety, sleep); moreover, the central pause is reduced to its more simple expression, to the point of being scarcely perceptible, even though it is this pause that makes life possible by enabling the body to feed off the energy contained in the inhaled air. The individual living in the world, however, being distracted from himself by his appetites and passions, has no awareness of the functioning of his organs, with the result that his body can snatch only that amount of the vital nourishment it needs to maintain a precarious existence. From the Shiva-Samhita

By control of the breath,
one gradually destroys all the karman
accumulated during previous existences;
one acquires miraculous powers;
one moves freely
throughout the three worlds!

The aim of pranayama is thus to control the energy released by breathing. In fractional terms this control takes the form of a progressive deceleration of the respiratory rhythm, achieved on the one hand by prolonging both inhalation and exhalation, and on the other (and above all) by increasing the central pause to its maximum.

5.pratayahara

6.dhrana

7.dhyana

8.samahdi