As a yoga instructor and practitioner, my experience is clients generally come to yoga for 5 main reasons:
1) Physical self-improvement
They are motivated by the prospect of toning the physical body in a gentle way. This may be an unconscious effort to appease or appeal to others or desire to meet the expectations of others.
2) Health
They are told practising yoga will bring them more energy, balance and overall well-being
3) Rehabilitation
They may have an injury and are working to regain range of motion, more mobility or stretch.
4) Personal growth
They may be on a spiritual journey, turning inward, sensing vibration, raising awareness, engaging in practices like mindfulness and meditation. Yoga serves as a stepping stone to live life more consciously from universal principles.
5) Intuition
They come guided by something they cannot explain, a deep urge to let go of fear and inhibitions, or as a stepping stone to other things.