Yoga is meant to facilitate union of the individual self with the cosmic. This could be achieved through inherent consciousness expanded within the body-mind growth.
There are four ways to try and do this: through spiritual action, discriminatory wisdom or knowledge, unassertive love and by deep meditation. Kriya yoga is a good mixing of all the four ways.
The word kriya suggests that to act or to perform. The kriya technique shifts your attention from sensory reactions to delicate perceptions within the brain and central system nervous to expand consciousness. Patanjali has stated 3 essential parts of kriya yoga: tapasya, swadhyay and Ishwarpranidhan.
They are interconnected. Together, the three comprise the path to indistinguishability. In isolation, not one in all them will provide the whole result of kriya yoga. Tapasya suggests that wilful withdrawal from sensual attachments and follow of some special psychophysical techniques or rites to elevate consciousness.
Swadhyay suggests that understanding lessons for fulfillment from scriptures. Human bondage is caused by ego.
Hence Ishwarpranidhan — providing all our endeavours and achievements to God and assertion of the spirit of temperament through surrender — paves the way for thanks to fulfillment.
To realise absolutely the, we want to elevate ourselves there to level by discarding the core of self-interest with a spirit of total surrender to the Supreme.