Sadhna- Spiritual Practices, is not just an exercise. It is the way to surrender your self, your thoughts, your emotions with each passing breath. Keep on praying to your master that I want to be useful, I want to do Seva, I want to reach to the Ultimate.
If positive emotion/thought comes, feel grateful and surrender it thankfully with outgoing breath. If negative emotion/thought comes up, just pray to Him to free you from that harmful tendency of the mind.
When you are offering your life in love to the Lord, it becomes your true Sadhna.