First of all, let’s look at this literally. In boxing/karate/MMA people “fight” by sparring. Some have to work up some intensity or think of angry things but most fighters I know look at sparring as a dancer looks at rehearsal. it’s about the good of the movement not about putting hurt on someone.
Some days sparring can be different. If another gym visits or there’s a rival within the gym or even if someone got the best of you the last time–you might turn things up a notch.
Fighting angry can be a big mistake if it is not channeled properly. it is exhausting and you can forget fundamentals and get taken a part. Marvin Hagler fought angry. Ray Leonard said he didn’t need it. They fought two different styles.
What about metaphorically? Can you negotiate the board room or handle a sales person by being assertive without a little anger? Does the absence of anger make us too soft? Would we be edgier if we let anger come in to play?
And long term what happens to people who let anger fuel them all the time? And fighters–can you sustain a career as an angry fighter? What happens when you age and you’re less angry? Or if you age and get angrier but don’t have the physical skills?