Lord Paramaśiva is Prakāśavimarśamaya , that is, He consists of Prakāśa and Vimarśa (Effulgence and Awareness of His own Effulgence).
In this way His Effulgence or Great Light is not at all something inert (devoid of any activity) as in the case of that Brahma worshipped by the followers of the doctrine of the Peaceful Brahma. His Effulgence is fully conscious of Itself through His Vimarśa (Śakti, the Power of the Great Lord).
All you can see right now is His Effulgence. By 'Effulgence', I do not mean mere physical light, but the substance that supports all the realities around you right now. At the same time, you are fully aware of these realities that are composed of Your own Light.
This awareness of Yours, which enables You to be fully aware of Your own Light, is known as Śakti or Vimarśa. And this Vimarśa is another name for Ānandaśakti or the Power of Bliss. And this Supreme Bliss is nothing but His Svātantrya or Svācchandya (His Absolute Freedom).
But what does all this really mean in practice? This: People who are not yet fully instructed think that a liberated person is someone who is ecstatic during his meditation session in the lotus posture or something like that. So they will look at that meditator and say, "Oh, he is really blissful." Anyway, when that meditator comes out of his formal cross-legged posture, he falls prey to every stupid thing that happens to him. In other words, he loses his Bliss completely.
At that time, those people will say, "Oh, he is not blissful now because he has fallen from his previous elevated state." This can be an appearance or an actual fact. If that meditator feels that his Bliss emerges only when he is meditating formally, then, it is true, he falls whenever he abandons his cross-legged posture and gets engaged in mundane activities, which are full of trifles. From where does he fall? From his supposed high state.
Nonetheless, if that person is a real liberated while living, a jīvanmukta, his fall is a mere appearance. Why? Because he experiences Bliss in cross-legged posture (during his formal meditations) and also when he is busy with worldly activities. His Bliss is not only occurring at the time of his formal meditation, but it is rather perpetual.
How could he achieve this? Through His Grace alone. That person does not feel, "This Bliss I feel during my meditation is real Bliss... but all this pain and lack of real Bliss I experience during the rest of my day is just... oh, this horrible ignorance!" NO, he experiences like this:
"This Bliss I feel during my meditation is real Bliss... and all this pain and lack of real Bliss during the rest of my day is also real Bliss... my depression is Bliss, my anger is Bliss, my happiness is Bliss, life is Bliss, death is Bliss, evilness is Bliss, goodness is Bliss, ugly people are Bliss, beautiful people are Bliss, peace is Bliss, war is Bliss...
"Everything is Bliss because all this is tadabhinna, that is, not different (abhinna) from Him (tad), from Paramaśiva who is my real Essence!"
That is the State of the Great Jīvanmukta or Liberated while living. In other words, he experiences all as Bliss and Bliss alone.
Thus, he lives in perpetual Bliss, without any interruption, whether his body is in the lotus posture or not, etc. He has the viewpoint of the Great Lord, because he can perceive Bliss even in what looks like complete absence of Bliss. This is his Great Achievement!
Spiritual aspirants who are still bound by their own ignorance believe that Bliss is only happening when they are "extremely happy" in meditation, chanting mantra-s and so on, while the rest of the states are full of "something else" (not Bliss). In this way, their Bliss lasts only as long as they are meditating, chanting, etc. in the lotus posture for example, but the rest of the day, when they are busy with "worldly" things, they are not in Bliss, but "sunk in misery". This erroneous concept as far as the real nature of Bliss is concerned is usually seen in this world.
But real Bliss is not like that, because if that were true, i.e. if it were true that Bliss is only lasting a while and the rest of the day one is sunk in "another thing that is not Bliss," such Bliss would be "divided" and consequently worthless. Who would want a Bliss like that, a Bliss that lasts only while one is meditating, chanting, etc.?
Such aspirants who are incapacitated by their own impurity (Āṇavamala) seek to make the rest of states apartf from the one they experience in meditation, chanting, etc. "blissful" too, but they fail miserably. Because they do not have to "make" anything, but only have the right attitude about the real nature of Bliss:
"Sadness is Bliss", "Pain is Bliss", "Worries are Bliss", "Stupidity is Bliss", "Happiness is Bliss", "Indifference is Bliss" and so on and on.
When they learn to consider all these states, generally branded as "worldly states," as Bliss and Bliss alone, they finally succeed. So, even if they are sunk in total misery, they will be replete with "undivided" Bliss.
This is the Key to escape from bondage, which is characterized by "absence of Bliss"... not because Bliss is not present in bondage, but rather because one thinks that this absence of Bliss is NOT Bliss.
Spiritual enlightenment is always about having the right attitude, Śiva's attitude (i.e. the right attitude about Bliss) and NOT about spiritual practices such as meditation, chanting mantra-s and so forth.
Source: Guru Gabriel Pradīpaka in The Paramārthasāra of Abhinavagupta