Resisting and holding on part 2

I don’t believe that this is part of the human condition. But I believe that many people, most of the time unconsciously, assume that it is. But why is it that we give some things a try, fail and conclude that it’s impossible, while we try other things, fail and practice for years? Why do we, specifically, often assume that we cannot unlearn the ways that we function and/or relate to our inner lives? I might not be able to make myself believe anything. But I know that I can challenge my thoughts. I know that one person shrugs his or her shoulders at a harsh situation, while another lets it ruin the day and perhaps even ruminates over it for a week. Considering that we do enjoy a certain degree of freedom when it comes to our thoughts, are these two, very different, ways of responding written in stone? Are they just unalterable parts of an inborn character? Or could we, depending on how we treat our inner lives, learn to respond differently to life? If we experience more suffering than we would like, would it be worth the effort to train ourselves to respond differently?