Many people claim to practice yoga but dont.
The Yoga tradition is aimed developing the mind through a path to enlightment. It is not merely to produce flexible bodies.
Most of the Yoga System of Patanjali is concerned with the science of meditation as concentration (mindfulness), meditation (freedom of the mind) and Samadhi (enlightment. These three stages are (Dharana, Dhyana, Samadhi).
The Yoga Sutras define Yoga as Samadhi or spiritual absorption.
So next time a person says they practice yoga ask them if they practice the below. If they dont, they are merely exercising the body.
8 LIMBS OF YOGA
Yama (moral conduct): noninjury to others, truthfulness, nonstealing, continence, and noncovetousness
Niyama (religious observances): purity of body and mind, contentment in all circumstances, self-discipline, self-study (contemplation), and devotion to God and guru
Asana: right posture
Pranayama: control of prana, the subtle life currents in the body
Pratyahara: interiorization through withdrawal of the senses from external objects
Dharana: focused concentration; holding the mind to one thought or object
Dhyana: meditation, absorption in the vast perception of God in one of His infinite aspects — Bliss, Peace, Cosmic Light,
Cosmic Sound, Love, Wisdom, etc. — all-pervading throughout the whole universe
Samadhi: superconscious experience of the oneness of the individualized soul with Cosmic Spirit