When we want to achieve something deep, physically, intellectually, emotionally and so on, we make a choice. A choice is familiar to anybody. How many times we wanted to take a class on Karate and never went back for some particular reasons. Or we made a choice to write a book but we ended up giving up after the first paragraph. I believe choice comes with motivation. The multiplicity of choices is practice.
And lets say that we continue to make that choice, not giving up that particular class, such as for example running. In that case we are practicing, our body begins making changes: losing weight, strengthening muscles, increasing lungs capacity, etc. In short multiple choices equals to a practice, and practice allows our body to create change. Hence the change is qualitatively positive.
Furthermore this is the points I wanted to emphasize: choice, practice, change and quality.
Most people associate practice with positive experiences. But when people do unhealthy things the word practice disappears in denial. Lets say that i am being lazy, slouching in the couch for hours. My mind is saying I should do this or it may say I don't care I love being lazy. The first case is denial, which means first I am making a choice of being lazy, second by continuing that inaction (which is still an action) I am practicing it, maintaining it or strengthening it. I am strengthening the lazy me by continuing its practice, like I would strengthen my body by practicing a physical exercise. Yet the change is with negative quality.
What then is the difference between denial or admitting it. The person in denial is not saying I am practicing laziness, alcoholism, drug use, and so on. She is saying I should not be sitting here all day, I should not be drinking so much. By saying or thinking that, she is not aware that she is actually practicing. And by practicing I mean strengthening an action, a direction towards maintenance and/or change.
We live in our mind, we believe our mind is action. In substance, inaction doesn't exist, anything we do is action, a practice that strengthens into us its qualitative effects. In short we become our practice or what we spend most of our time in.