From the Yoga Sutras of Patanjali (2.1) as translated by Rev. Jaganath Carrera….
“Kriya yoga, the three elements that form the foundation of the yoga life, are:
Tapas — self-discipline and accepting hardship and pain as a help for purification
Svadhyaya — repeated, deep study of sacred wisdom and the introspective search into the nature of the self; mantra repetition
Ishwara pranidhanam — wholehearted devotion and dedication to Ishwara [God, Divinity].”
Practice these and reap the deepest benefits of Yoga!
Here’s a related teaching from the Christian Bible:
“Endure hardship as discipline; God is treating you as his children. For what children are not disciplined by their father? No discipline seems pleasant at the time, but painful. Later on, however, it produces a harvest of righteousness and peace for those who have been trained by it.” (Hebrews 12: 7, 11)
Holistic Yoga & Spiritual Guidance 