Our own individual existence is due to combination of material and mental elements along with presence of cosmic spirit Brahman/Atman (soul) within boundary of physical body.- 
 1) Material body consist of five elements, form, ten senses which include five internal senses e.g. the eyes, Ears, Nose, Tongue, skin and five organs of action e.g. voice, legs, hands, anus and genitals. Five external sense bases also called sense objects e.g. Visibility, Sound, Smell, test, Texture. One vital breath which have five different names according to its functions. This five breaths are a) Prana- this vital breath is located in the lungs. b) Apana-this breath is located in lower regions c) Samana- this has its seat in navel area d) Udana- this functions near the throat e) Vyana - this pervades the all body. Unstable nature of mind is caused due to fickleness of this five kinds of air. 
2) Mental elements - mental sense organ mind, Intellect (Aspect of mind which reflects wisdom and ability to understand the difference between Good and bad), Feelings/sensation (both pleasant and unpleasant), Perception (the aspect of mind which grasps or identifies characteristics), Desire (state of mind that strongly wish for or want something), Conviction or belief (State of mind which accepts ideas or concepts to be true or false with factual certainty based on past experience and knowledge), metal formations (Suksma sarira which have all types of mental imprints and conditioning triggered by an object) 
Three types of consciousness which have sense of false ego- 
a) Waking stage - Vishva /Vaisvanara or the waking consciousness characterized by the individual gross body or sthula-sarira. In waking consciousness we are aware of our daily world. In the waking consciousness there is a sense of 'I' [self-identity] and awareness of thoughts. 
b) Dreaming stage - Svapna/Taijasa or the dream consciousness which has the subtle body or suksma-sarira as its object. It is described as inward-knowing (antah-prajnya), subtle (pravivikta), and burning (taijasa)". This is the subtle body.
c) Deep sleep –In this stage the underlying ground of consciousness is undistracted. In the sleep/dream state there is no or little sense of 'I'; however, there are thoughts and the awareness of thoughts. Waking and dreaming are not true experiences of Absolute Reality (soul) and metaphysical truth, because of their dualistic natures of subject and object, self and not-self, ego, and non-ego.

All above elements are called as field of Activity. This field of activity consist of Prakriti/energy of Cosmic spirit Brahman/Atman (soul). Prakriti is Maya and it is of two types. First one is Para Prakriti this is pure energy existing in universe also called as extraordinary energy of cosmic spirit and second type is Apara Prakriti this is lower nature of energy and is combination of all mental and material elements. This Apara Prakriti is under the influence of three (Gunas) modes of nature (the three modes, or qualities of material nature; goodness, passion and ignorance) which cause the creation of all human being and the world. All these material and mental elements are in a constant state of flux. Our existence it due to interaction and of these material and mental elements along with existence of cosmic spirit within boundary of our physical body.

Liberation is nothing but knowing true nature of us/soul. Liberation can be achieved by destroying false ego. False ego is when one consider himself to be physical body and is always busy in satisfaction of this organs. When soul identify itself with material body and mental elements through mind (when mind become slave of senses without attending to intellect /object of mind is physical organs and sense objects) it/soul gets trapped in cycle of birth and death. One should know the impermanent nature of physical body and mental elements. Our thoughts and feelings are conditioned and are always changing. Our body grows old and with time it wears out and finally it dies. But our true nature which is soul is ever permanent and eternal. When mind which is attended by pure consciousness/soul is busy in sense gratification and in materialistic world it causes Karmic accumulation in casual body (according to Upanishads human beings have three bodies. These are a) casual body/Karana sarira, b) subtle body/astral body/sthula sarira/Linga sarira,c) gross/physical body/Sthula sarira) . This Karmic accumulation/mental imprints which are stored in casual body are the reason of the soul to get trapped in cycle of death due to cause and effect principle and it accepts new physical bodies according to this impressions of experience. When our mind is focused on our inner self without identifying self with body (the object of mind is mind itself which in turn is focused on our soul/pure consciousness) through devotion or meditation and different yoga practices our soul cease to identify itself with three types of bodies. Our existence due to three types of bodies cease to exist and soul stops identifying (superimposing) itself with three bodies and thus freed from cycle of death and birth.