Change is a process.
I suppose sometimes change happens, and we react, adjust, roll with it.
But internal change is a process. It takes time and proceeds in stages, by fits & starts. The first is becoming aware of a need and/or desire for change. Identify the problem. It required introspection & honesty, which can be very difficult.
What I find more painful is the next stage. I know what I’m doing “wrong”. I can see myself doing it, returning to an old habit that I’ve found damaging or isolating. But all I can do is watch. I don’t know how to stop it.
Yet.
I have hope I will learn. And in the meantime, I will try to be lenient with myself. It takes time to replace old habits built & reinforced over years, to learn new ways.
Change is a process. I’ll will find my way through it. But it will take time.
Ever on & on 
Everything worth doing takes time. I’ve found that when I focus on what I can do today, the future takes care of itself. And as the book says, we may be through with the past, but the past ain’t through with us.
But as you write, we learn. And we grow. Our past is the soil in which we are planted. But it’s the light and the rain that makes us grow.
Indeed. If you want to dive into changing habits more, have a look at Charles Duhigg’s book ‘The Power of Habit’ (there’s a formula in there that seems pretty robust). But as you say, it takes time. Small victories can add up! (and there are so many habits I want to change- but one at a time).