"There is no self to be dissolved, only the notion of self to be transcended." -Thich Nhat Hanh
Self is a notion of separation from other people and things. From the moment we are born we begin to take in our own air and demand our own food from the environment. No longer is the newborn completely cared for in the womb. They must exert themselves in order to get what they need. This is the most primal expression of self. The self that perseveres. But as we age the concept of self expands from basic bodily needs to emotions and thoughts that arise from within. Our experiences and family backgrounds give shape to these thoughts and impulses, collectively defining them as personality or self. Ideally, as we age the concept of self will continue to expand, eventually outgrowing just the confines of our bodies and minds to contain our family and friend networks, our community and nation, our species, and our planet. The Buddhists speak of the large "s", Self, as containing all existence.
Yet, for many of us we can get stuck somewhere along this expansion. Our concept of self stays stagnant at the level of the ego. We vie to preserve the status quo that has been set during adolescence, consequently leading to what we will call selfish behavior. The ego is the enemy, as Ryan Holiday put it in his book on the subject, to us leading fulfilling lives. The ego is constantly trying to keep the world still, validating itself by criticizing others. If we wish to overcome its gravity, then we must start practicing engagement in discomfort. The ego thrives on comfort. What is known is comfortable. What is unknown is threatening. The ego would much rather live in a well-defined prison with all of the usual amenities, than risk having to step out into the real world and engage with new, potentially life-altering, challenges. So, as sentient beings we have a choice to make each and every time we feel discomfort. Will we default to our normal patterns of self before others, or will we embrace the challenge of finding self with others? The ultimate goal of Buddhism is to blend the cares and needs of the self with cares and needs of others, seeing no distinction between the two. By helping others you are helping yourself, and vice versa.
These are dense and esoteric topics, that must necessarily be grounded in the day to day. We can take this from two angles. What kindness have you shown yourself today? What kindness have you shown others? If both of these can continually be answered by something substantial, then you are on the path I'm describing. This won't be easy, and often we will have to slay our own self image to do the right thing. Trust your heart and be brave.