Many of us have scar stories. We can point to a scar, say, above our eye and recount exactly what happened on that day years ago. We can remember details, imprinted on our memories despite how long it's been since it happened.
Scar stories are one thing. But live long enough and we get other scars--often emotional scars. We tend to remember the bad, more than the good, especially when things are not going well. There's a soundtrack that runs in our mind, often played and replayed, telling us it won't get better.