The false ascetic begins by being cruel to everybody because he is cruel to himself. But he ends by being cruel to everybody but himself. Merton, No Man is an Island, pg. 96
Merton highlights the importance of rooting the acts of spiritual disciplines in self-love not self-loathing. It’s easy to allow our frustration with ourselves to drive us to work harder at self-improvement. But this only perpetuates a cycle of self-hatred which spreads to others-hatred. Spiritual disciplines that bring about the desired growth effect are those rooted in self-love. When we love the person God has made us to be and believe that we can achieve the dreams he has planted in our hearts, self-discipline finds the fuel it needs to succeed.