By spiritual experience throughout the centuries it has been granted by men that life has a goal. According to the teachings of Veda, Upanishads, epics the goal is to realize God or to realize one's perfect nature. Four major methods are described to achieve this goal of life which are called as yoga or the paths of realization. One of the four aspects of human nature dealt with each of the four yogas. we all have three inner faculties of thinking, feeling and willing. The yogic condition arises when three faculties of our inner self not working properly or actively. So these are the four possible states of mind; the mind thinking, the mind feeling, the mind willing and the mind in its quiescent form. Based on these views there are four yogas:jnana yoga, bhakti yoga, karma yoga, and raja yoga respectively. So anything connects or joins us to the lord or the ultimate reality is to be considered as yoga.
Vishada yoga or the yoga of dejection is described in the first chapter of Bhagabat Gita. We must think that how dejection be a yoga. Dejection pushed Arjuna into a search for the higher reality and into surrender to the Lord. Gita is all about the Kurukshetra war in which two opposing partys of a same family standing against each other to fight. Arjuna was a commanding general of one side, but on the other side his own brothers and friends. So he was very much depressed about what to do. Krishna was Arjuna's charioteer, so Arjuana asked him, "I am getting confused. What shall I do?" Then Arjuna continued "O Lord I am your disciple. I take refuge in you. Please guide me." In response Krishna gave the whole teachings of the Bhagabat Gita. So the conclusion is that anything that pushes a man towards, first, a deeper search, and then, deeper realization is a Yoga. There may be some other varieties of Yoga but the basic yogas are four. All other yogas can be put under one or another of these four.