When we experience peace and joy, our state of mind is said to be positive. When we experience negative emotions like anger, hatred, ill will, fear, depression, anxiety, and so on, our state of mind is said to be negative.
When we experience a negative state of mind, is it possible to utilize the understanding of 'nothingness', 'change' and 'non-duality' as a tool to change our state of mind into positive? Yes!
The key idea to developing non-attachment is to remember the following: 'What am I angry about? What am I afraid of? What am I anxious about? This experience that I'm having is dream-like; it does not have its own independent existence; it occurs in me! It's my own experience, not separate from me. Then why be afraid? Why be angry? Why be anxious? Be at peace and smile :)"
An intellectual understanding of the concepts of 'nothingness', 'change' and 'non-duality' is not sufficient to experience peace n joy. We have to develop non-attachment in our daily life.
Once the concept of non-attachment / acceptance is understood, the concept of Karma Yoga can be understood:
In Roman script:
Translation:If we understand the answer to the 'Who Am I?' question but fail to practice non-attachment, then we have developed ourselves intellectually but failed to apply that knowledge towards excellent personal conduct in our day to day life. This point is explored further in Daily Practice.
Non-attachment is a delicate concept. It is identical to 'acceptance' in Sufi and Bhakti poetry. It should not be confused with 'apathy', 'resignation' or 'becoming a vegetable'. A good article that explains non-attachment is Let Go, Find Peace.
Non-attachment is the same as acceptance in Sufi & Bhakti poetry. It would be helpful to browse through What to Accept? Whom to Love?
Swami Sarvapriyananda has dozens of lectures on Advaita Vedanta online. One lecture that I really liked is The Way of Love (62 mins, 2017). This lecture is an exposition of 'Bhakti Marga' (the 'Path of Love'). Early in this lecture, he mentions that traditionally, Advaita Vedanta was taught to advanced students: those who had done several years of meditation, who had renounced worldly belongings, and so on. An untrained student, even after gaining an intellectual understanding of Advaita Vedanta, keeps wondering, 'so what? how does this understanding impact my life?' Such students may miss the connection between an intellectual understanding of Advaita Vedanta and its application to our day to day life. The bridge that connects intellectual knowledge and worldly conduct is important: it is the practice of non-attachment.