Yoga is an integral approach made of eight limbs (Ashtanga) working together in harmony for a single purpose of promoting wellness in you.
Can you imagine a life filled with wrong personal and social conduct, ruled by the five senses, and only guided by the emotions? Can you imagine this life producing peace, health, and happiness? You cannot! It is not possible. The emotions are a good servant but not a good master. The intellect is the master and must take charge.
Imagine your body as a chariot, your intellect as a chariot driver, your mind as the reins, your five senses as the five horses drawing the chariot, and your desires as the roads you travel on. Your intellect must at all times be in control of the reins (mind) and direct the horses (senses) to keep the chariot on the right roads (desires) for creating wellness. Otherwise, five horses (your five senses) running wild and out of control would drive the chariot (body) on the wrong roads, creating disease and unhappiness.
Try to understand that yoga is more than just physical exercises. When you practice all eight limbs of yoga, including right thoughts, words, actions, social behavior, physical exercises, self-control of vital life forces, and self-control of mind with vigilant intellect, then you unite your spiritual, intellectual, emotional, and physical components all behind one single purpose, and that is wellness!