This is quite clear to me. Sometimes it is very stubborn and very difficult to change. But with continuous effort and with conviction based on reason, our minds are sometimes quite honest. When we really feel that there is some need to change, then our minds can change. Wishing and praying alone will not transform your mind, but with conviction and reason, reason based ultimately on your own experience, you can transform your mind.
Time is quite an important factor here, and with time our mental attitudes can certainly change.
One point I should make here is that some people, especially those who see themselves as very realistic and practical, are too realistic and obsessed with practicality. They don't contribute in any way to the transformation of one's mind or to attaining some kind of mental discipline because they are completely unachievable. Some people may think in these terms and feel that perhaps a more effective approach would be to begin with a close circle of people with whom one has direct interaction. They think that later one can expand and increase the parameters. They feel there is simply no point in thinking about all sentient beings since there is an infinite number of them.