Yoga means union of soul, mind and physical body to attain unification with higher powers termed as God. The most important benefit of yoga is physical and mental therapy. Aging process which is largely an artificial condition, caused mainly by autointoxication or self-poisoning can be slowed down by practicing yoga. Yoga involves physical exercises and meditation to get benefits which has not been seen or possible with other forms of exercises which includes stretching etc. Yoga involves several exercises which work on joints, bones, cartilage and muscles. It also affects internal organs which includes our nervous system, hormonal system etc. Majority of yoga asana work on our back bone or spine stretching, strengthening and increasing its flexibility. The question arises that after 18 years, is there any possibility to increase height? The answer comes to be yes. Yoga works on our spine where intervertebral discs are compressed. Yoga utilizes the decompression to increase height. Further between 18-22 years of age, your growth plates are not fused 100 % therefore we expect some results at the end of long bones also.  

Further in response to continuous slow stretching of limbs, Yoga utilizes cartilage thickening, ligament and tendon stretching to increase height even after 18 years of age. Results are seen till 32 years of age where it is possible to increase height through yoga.

Yoga exercises include several asana, out of which some are mentioned to help out .