Has anyone ever thought about self harm but never does it?

I was diagnosed with PTSD, depression, and anxiety. I've been going to therapy for about 3 years now. I always think about self harming (for years) BUT I never do it. I'm proud of myself for not hurting myself. My best friend self harms and she tells me I'm weak and I'm seeking attention by saying that I think about doing it but I won't commit to it.