Yoga is one of the best systems in the world to have a healthy and beautiful life. Actually yoga is meant for the mind to reach a higher level, to have an unshakable mind with clarity. Unfortunately, today most people see yoga as asana.
Patanjali's yoga sutras places Asana in the third place. Before coming to asana, one has to have discipline with others and in the outer world, which is called Yama and the need for discipline within oneself is called Niyama. After Asana, Pranayama comes, Pratyahara (control over the senses), Dharana (being for a long time with an object without disturbance) and then he brings in Dhyana-meditation in the eight limbs of yoga-Ashtanga.
If we master the first five aspects, the rest would be very easy. One step helps to reach the other step.
Many texts say that yoga is an Indian system more than five thousand years old. Today on a large scale people are practicing it in many countries. There are so many types of yoga and each one has its own benefits.
There are references about yoga in Vedas, Upanishads, Bhagavat Gita... Patanjali's (who is considered as one who systematized yoga) Yogsutra text is respected and accepted by many yoga gurus as an authentic text.