What we pronounce as Yoga, has the form yogaḥ in Sanskrit and it is derived from the Sanskrit root ‘Yuj’, meaning ‘to join’ or ‘to yoke’ or ‘to unite’. It means communing with the absolute, non-changing constant that we may call Consciousness or God or Oneness or Is-ness. (Names are many, but the name is not the thing). Doing this requires that we transcend our current paradigm of thinking, behaving and choosing. To ‘ do’ Yogaḥ is to first and foremost bring about a perceptional, attitudinal and behavioural change in ourselves with regard to people, other beings and the world around us; to sensitize ourselves to see the higher reality, which is subtle yet all-pervading, which illuminates and animates our lives and which is the ultimate truth, meaning, freedom & harmony within us.
Based on the context where the word is used in Sanskrit, it can mean absolute knowledge (wisdom) or discipline. Disciplines are mainly two-fold, one that is followed for gaining the mental preparation needed for knowledge is karma-yogaḥ, whereas discipline followed for the attainment of that knowledge is called jñāna-yogaḥ.
Yogaḥ as a discipline:
When referred to in the context of discipline it means karma yoga. An action performed with the proper attitude, in conformity with universal values is known as karma-yogaḥ. Karma-yogaḥ serves as a preparatory discipline for pursuing the self-knowledge that leads to mokṣaḥ or liberation or ultimate freedom.
Krishna in the Gita defines Yogah as ‘yogaḥ karmasu kauśalam’, discretion in action is yogaḥ. Kauśalam is our capacity or skill to interpret situations on a day to day basis with reference to norms of human interaction and making decisions effectively. This requires skill and one can develop expertise in the same eventually. The norm for human interaction is called dharmaḥ, the right thing to do in a given situation. So the ability to properly interpret dharmaḥ is called kauśalam. This Kauśalam is yogaḥ because the course of your life is no longer steered by the ways of our rāga-dvesas, likes-dislikes.
An expert in the practice of karma yoga, is called Yogarudha- a person with adequate discipline and mental preparation for the pursuit of knowledge. Such a person is definitely ethical (may not be religious) but is committed to and prepared for the spiritual pursuit.
Preparatory disciplines are many. There are many disciplines to help one prepare one’s mind for self-knowledge and since each mind is unique as well as common, it may require a combination of common and specific prescriptions for mental preparation. Dharma or living a life of ethics and values is the common prescription. The specific prescriptions are chosen based on one’s physical and mental constitution and tendencies. For example, Hatha Yoga (which is part of Ashtanga yoga of Patanjali) prescribes yogic exercises of stretching and breathing (pranayama) to calm the mind and body. Similarly, there are the paths of devotion (bhaktiḥ) as well as meditation/ worship (upāsanam) to specific names/forms. Since all these are expressed through actions alone, they come within the ambit of karma-yogaḥ.
Yogaḥ as absolute wisdom:
Once the mind is prepared using the discipline of Karma yogah, the pursuit of wisdom starts bearing fruit. The pursuit of understanding or wisdom is also a discipline and is called jñāna-yogaḥ. It involves three steps – śravaṇam, mananam, nididhyāsanam which lead us to the attainment of knowledge, Jnana.
This path consists of śravaṇam, constantly and systematically hearing, for a length of time, the guruḥ unfold the Upaniṣads, then (with the help of the guruḥ) removing doubts and misunderstandings from what has been heard (mananam) and, finally, dwelling (nididhyāsanam) upon what is properly understood of the true nature of the self as taught by the guruḥ. It is living a life devoted to knowledge of the self, ātmā-jñānam.
Although jñāna-yogaḥ is the true solution for existential and emotional sorrow, many are not able to discover that fact due to their delusion that the world is a source of happiness. They need to discover for themselves that actions and their results can give at best fleeting access to happiness. Such growth in dispassion is essential for the successful pursuit of jñāna-yogaḥ. That is why karma-yogaḥ is a necessary prerequisite intermediary stage to come to jñāna-yogaḥ.
All mind preparations have to lead to Jnana Yogah and only by Jnana can there be Moksha. Mokṣaḥ is freedom from self-ignorance and ignorance that leads to misperception of both oneself and the world. These misperceptions result in misconceptions that often evoke misplaced emotional responses in the form of unease or distress (including jealousy, anger, depression, fear, anxiety, regret, etc.) too often resulting in inappropriate action and sorrow. All such unfortunate responses leave a residue of unfinished business that perpetuates the cycle of emotionally driven problems known as saṃsāraḥ, a cycle that is never-ending until broken by correct knowledge of oneself and the world. That is where Yogaḥ comes in. So the ultimate goal of all Yogas is the same, Moksha. The process or the path to Moksha is Yoga.