Goal of Life
Yoga is not just performing a set of postures, although that is the main thing most people know of it. Practicing Yoga is a means whereby you are bringing your physical self, mental self and emotional self to as perfect a state as possible so that Divine Union can take place.

If your physical body is full of blocks and pollution, Divinity will not descend. Divinity is perfection and will go only where perfection is. If your mental body is full of all kinds of disturbances, with thoughts out of control, i.e., your mind controlling you instead of you controlling your mind, you will not be able to control it long or effectively enough to experience anything on that plane. And if your emotional state is in constant turmoil, you will not be in control of anything at all and will be swinging wildly back and forth in all circumstances. Hatha Yoga is the means for gaining control of each layer of the body from the physical, to the vital,  the mental or emotional, to the, intuitive, until it finally reaches perfection or Bliss layer.

This is the goal of life; the only reason for being given this very birth. And the great ones have come to tell us time and again that each and every man on earth has the capacity and the means to reach to this goal in this very lifetime. Yoga is the means given to us by the Divine itself to attain nirvana.

Union with the Divine
Yoga is a the science of Spirituality. Yoga means Union, Union with the Divine, Supreme Consciousness. The great Masters have come to tell us that this experience and this experience only will take away all of our sorrows, misery, problems, fears, and suffering. We are ignorant of this great Truth, and therefore suffer needlessly.
Yoga tells us that through this Union, we will experience Truth and the great folly of this ignorant life will be destroyed once and for all. Then and only then will we be in a position to truly propagate Truth and help our fellow man. Then and only then will our life have meaning and purpose.