Because we have suffered, and we are not afraid to suffer in order to survive, we are ready to give up everything - even our lives - in our struggle for justice.
If you are interested in preventing animal suffering, the first thing you should give up is eggs and milk, because the animals who produce those foods lead the most unhappy lives. You would do better to eat meat and stop eating eggs and dairy products.
When workers fall back on violence, they are lost. Oh, they might win some of their demands and might end a strike a little earlier, but they give up their imagination, their creativity, their will to work hard and to suffer for what they believe is right.