I think what Krishnamurti is saying is that in wanting improvement, I am being judgmental, critical and condemning of myself or some aspect of myself which precludes awareness that is mindfulness. Awareness that is mindful is observing of my action in a way that is simply witnessing, and not judgmental or condemning. Change occurs with such nonjudgmental observing. Wanting improvement is being goal-directed, trying to steer and force a certain change, and mindfulness is witnessing which allows for change to happen. I think Buddha and Jesus were each being nonjudgmentally aware in dealing with temptations that they didn't condemn or attach to and did let go by. A personal example of experiencing communion between the observer and the observed has to do with my anxiety. I'm good at generating anxiety in myself. When I judge, criticize, and fight it, I get fixed on it and stuck in it and my goal directed efforts to get rid of it make it worse. To the extent I observe, accept, and allow myself in the moment, I am one with myself and am at ease, in which process self-improvement happens as a byproduct of my mindful awareness. Awareness allowing improvement is different than trying to make improvement, which difference reconciles the practice of self-improvement with the author's criticism of it.