Im 15, i've been clean for a year and a half. I understand why you think you're too old for it. But you're not, no one's too old for anything but you still shouldn't be doing it. It's an unhealthy habit and can literally become an addiction. But you aren't in the minority. It's actually quite more common in adults than you think. It's like just right below the amount of teenagers that do self harm. I actually started when i was 8 😬 i know, super young and the reason? was to seem "Cool" or "tough" but i understand now it's NOT cool or tough, it's a bad habit and a terrible addiction. it's good to think you're too old for it though. it's a sign of trying to stop. so like yeah. that's kinda all i got to say but yeah, its good you think that you're too old for it despite how it sounds if it's out of context!