To me, with a little "y", yoga is a set of stretching exercises that are sometimes relaxing and sometimes stimulating It's good for relieving tension, improving the range of motion of joints, and boosting circulation to muscles thereby facilitating healing of injured tissue.
Yoga with a big "Y" is much more. It's a philosophy. It's a lifestyle. It's a 5000 year old system that heals the body, the emotions, the intellect and the spirit.
In Sanskrit, yoga means "union." But of what to what?
To ancient practitioners, it meant union of the being with Spirit, the all pervading and all encompassing energy of the universe that weaves through every animate and inanimate object. Yoga trains one to resonate with all beneficial levels of that energy.
There's no interference with religious teachings. Rather, Yoga can strengthen and add dimension to any faith. For atheists, the science of modern physics acknowledges that all is energy in many forms, matter in a matrix of interchanging states.
From a healing perspective, Yoga is the union of our individual being with nature, with what is a simple and beneficial in our environments.
It's a choice to live a disciplined life that resonates with the pulsations of a higher meaning. It's a way to stay physically healthy, to balance our emotions, to choose to live wisely in communion with the all that is one, that is "us" in myriad manifestations. Yoga is a tool, a gift, that when practiced fully leads one to freedom.
Ultimately, Yoga is a way of living, a path of transformation and personal growth, a tradition of learning that strengthens our morality, tunes our anatomy, deepens our breath, expands our consciousness, and unites us with the eternal flow of universal energy. It is a holistic discipline for health and happiness.