That really is some beautiful writing. The part about facial scars rings true for me. Every morning I look at my forehead, where my helmet prevented some serious damage after a serious nightcap, and the faint line left under my lip when I did a swan dive into the shallow end of a pool.

I like the idea of internal (non-physical scarring) because it makes me wonder what kinds of shapes they'd take. For example, we all know what kind of scar a cut, a burn or a broken bone leaves, but what is the shape of the scar left by getting jilted?

Your writing exercise reminds me of one I used to conduct with my own classes. It's a fairly well-known exercise, though for the life of me, I can't recall whose it is. It begins by looking at one's own hands in detail and imagining them as they were when one was a child, then when one is very, very old. The next part of the exercise is to do this for someone one knows very well, filling in all the details of the changes and their backstories. The final part is doing the same again for a character of one's own creation.

It's a bit involved, but doable over three class periods with homework assignments.