There are three principles mentioned in the Bhagavad Gita.
- Impermanence of the body
- Immortality of the soul
- Man’s individual duty
What is most essential is to put these principles into practice. This is sadhana. When we perform actions, we get immersed in imagining how things will turn out and what benefits we will secure. Working selflessly and without expectation secures greater happiness because we are fully absorbed in what we are doing. Sadhana is selfless action that pleases God, offering all to Him. When every action is dedicated to God without attachment to the fruits, a great power is generated. It becomes Karma Yoga.