I'm interested in starting doing yoga. 
yoga is great its physical, spiritual and mental disciplines from India
What kind of spiritual things does it involve?
Yoga
Yoga (; ; ) is a group of physical, mental, and spiritual practices or disciplines which originated in ancient India. Yoga is one of the six orthodox schools of Hindu philosophical traditions. There is a broad variety of yoga schools, practices, and goals in Hinduism, Buddhism, and Jainism. The term "yoga" in the Western world often denotes a modern form of Hatha yoga, yoga as exercise, consisting largely of the postures called asanas.
The origins of yoga have been speculated to date back
advaita teachers are H. W. L. Poonja, his students Gangaji Andrew Cohen, Madhukar and Eckhart Tolle.
Asian cultures and religions Hinduism Yoga.
The prime means to reach moksha is through the practice of yoga (Sanskrit, Pāli: , /ˈjəʊɡə/, "") which is a commonly known generic term for physical, mental, and spiritual disciplines which originated in ancient India. Specifically, yoga is one of the six "āstika" ("orthodox") schools of Hindu philosophy. It is based on the "Yoga Sūtras of Patañjali