In the beginning, a little self-interest is okay. Even if a person does good out of fear or for personal gain, they are still moving away from negative actions and that’s the first step. Karma gradually purifies the mind. When we repeatedly practice kindness, forgiveness, or service, our way of thinking begins to change we start doing good not for results, but because it becomes our nature. This is the true essence of Yoga. The Bhagavad Gita says “Do your duty, but do not concern yourself with the fruits.” So even if your reason begins with self-interest.