There are many different kinds of Yogas (Jnana, Bhakti, Kundalini, Karma, Raja, etc.), but people usually think of Hatha Yoga, the physical exercise Yoga, whenever they see the word. All Yogas are are methods that can be used to help people live spiritually, it's pretty much a way of meditating. If you practice Hatha Yoga and that isn't your goal, it's not really Yoga, it's just stretching and balancing. There's a lot more than the physical aspect of it that makes it Yoga. It is sad how commercialized it has become.
I'll type out a section from my eastern religions book.
Hindu Meditation: More Than Emptying the Mind
Over the past three decades, meditation has become popular in the Western world. From students in elementary schools to executives in corporate offices, all kinds of people take time out to sit quietly, empty the mind, and let stress float away.
Meditation in Eastern religious traditions, however, is more complex, at least theoretically. The Yoga Sutras, often attributed to the grammarian Patanjali, list eight steps necessary for perfection of meditation:
- Self-control (yama) is the fundamental reorientation of the personality away from selfishness. It involves practicing ahimsa (not hurting living beings), exhibiting sexual restraint, shunning greed, refusing to steal, and embracing truthfulness.
- Observance (niyama) is the regular practice of the five preceding virtuous pursuits.
- Posture (asana) is an integral aspect of meditation, particularly the "lotus posture" (padmasana), in which the person meditation is seated with the legs crossed, each foot touching the opposite leg.
- Breath control (pranayama) involves deep, regular breathing, holding the breathing, and breathing in various rhythms.
- Restraint (pratyahara) helps the meditator tune out external distractions.
- Steadying of the mind (dharana) teaches the meditator to focus on only one object in order to empty the mind of everything else.
- Meditation (dhyana) occurs when the mind is focused only on the object of concentration.
- Samadhi is the mental state achieved by deep meditation, in which the individual loses the sense of being separate from the rest of the universe.
Any systematic set of techniques that leads to greater spirituality can be considered a yoga.
Here's a good quote that I think relates to eastern philosophies and what is often realized through meditation:
"A human being is part of the whole called by us “universe,” a part limited in time and space. We experience ourselves, our thoughts and feelings as something separate from the rest. A kind of optical delusion of consciousness. This delusion is a kind of prison for us, restricting us to our personal desires and to affection for a few persons nearest to us. Our task must be to free ourselves from the prison by widening our circle of compassion to embrace all living creatures and the whole nature in all of its beauty… We shall require a substantially new manner of thinking if humankind is to survive." - Albert Einstein