A street thug and a paid killer are professionals - beasts of prey, if you will, who have dissociated themselves from the rest of humanity and can now see human beings in the same way that trout fishermen see trout.
I don't need to convince anybody that I know kung fu, but maybe somebody needs to know that I really can act, without doing a Chinese accent or a funny walk.
I had never done Shakespeare before, but I don't think you can be an actor and not do it. There were moments when I thought, I'm just not going to be able to pull this off.