Yeah, as long as you feel sorry for what you did.
I was the... 'anti-bully'. I used to get the s**t beaten out of me in primary school regularly and that sort of toughened me up. A few years later I'd gotten taller than most people, broader (my shoulders are a few feet apart ), and a few marks from the damage I used to take.
Not the main effect of all this was one thing. It toughened me up, and hardened my attitude towards bullies. I spent the last few years of high school looking out for my group and the very last teaching them a little self defense.
And, well the whole thing left me feeling a little vigilantistic. If I see someone beating on someone else I feel the need to step in regardless of damage to myself. Can't break what's been broken already.
But whatever the case, I think the main thing is having empathy. If you do something to others you should feel sorry for it later. I feel sorry for both the people I stop from beating on others, and the dentists who have to fix their teeth. ><
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A definition by words is merely a means to deceive oneself. It's meaningless before the truth. What matters is how you perceive things. The slightest shift, then life and death no longer have any meaning.