When I have "down time," I worry about self harm too. I always have down time in October so last year I decided to try to do the opposite of SIB. I decided to pamper myself everyday. I would do things like taking a bubble bath, I exfoliated my whole body (that feels great btw), I'd drive to Starbucks and get my favorite, vente pumpkin latte. Other ideas... go get a mani or a pedi, schedule a massage, see your stylist and have your hair done. Do a little retail therapy, like buy something for yourself that you've been wanting but normally, you'd never buy for yourself and you'd just hope someone gives it to you as a gift. But hey, just go buy it for yourself and you don't have to hope and wait.

I don't know if you would be into this sort of thing exactly but if you can find a focus, it helps to distract from SIB.
Good Luck, big hug.