I first started self-harming in my mid-20s. And for me it was a way to redirect my bad feelings, or to over-ride my bad feelings.
Self-harming would also include putting myself in situations where I would feel shame. The shame was very effective in changing my emotional landscape.
For me I would also include: abusing drugs and alcohol as self-harm…and for me, binge eating too.
As I have matured, I self-harm less. So thankfully it’s a rare thing these days.