I started cutting around the age of 15, back when I started struggling with depression and mania as a result of the onset of bipolar. It's a stress reliever...I often feel like there's a lot of emotional pressure building up inside me and self-harm was a major way of relieving it. It's been on and off for the last 11 years, and I'm prone to the occasional relapse. I haven't done it for a couple of months, though.
I've never cut deep enough to warrant medical attention, but my left forearm is still heavily scarred, almost like a washboard. I used to wear only long sleeves in public but now I've relaxed a bit and wear a sweatband over the area.