[Note: I italicize phrases I borrow from the chapter, and link to phrases I borrow from other chapters to help tie chapters together. While making it more tedious to read, the Tao Te Ching is best pondered in the context of the whole.]

Notice how all three ‘One who excels’ scenarios have emotional equanimity in common? Being roused in anger is the most obvious loss of such cool. Even so, an overtly ‘tough’ person’s appearance of formidability belies a lack of emotional equanimity (i.e., a lack of emotional security). It appears that everything we do, and how we do it, springs from a visceral need to maintain balance (i.e., emotional homeostasis). So, for example, in feeling insecure I may be driven to put on a ‘show’ of security (act tough) in an attempt to compensate. Or I may avoid situations that feed into my insecurity. On the other hand, feeling angry(1) or argumentative, I’m easily driven to join issue and fight because victory promises me a sense of balance, illusory as is. In short, we don’t ‘act’ in life; we ‘react’ to life according to how life’s circumstances trigger emotion, with fear being the ‘black hole’ at the center of emotion’s core.

The less driven by emotional necessity we are, the more conscious we can ‘react’ to life’s circumstances. This is not to say we should ‘control’ our emotions, even if we could (i.e. free will). Frankly, we can never simply ‘let go’ of fear. Ironically, just the opposite works best… embrace that ‘black hole’, hold fast to the void and do my utmost to attain emptiness. This makes it easier to know and accept the how and why of what we do. This heightened consciousness of what we do and how we do it is often enough to keep a thing in order before disorder sets in. Finally, doesn't excelling in anything require us to 'keep it together'?

It appears that two factors are at play here: namely, how intense the emotion we feel at the moment, and how deeply we know the ‘game’ that is going on behind the life’s curtain. Here is at least one great advantage growing older – emotional intensity tends to goes down and experience in the ‘game’ tends to goes up.

Today's literal translation:
One adept in serving as a warrior or scholar is not martial
One adept in fighting is not enraged.
One adept in victory over enemies does not participate.
This is called the moral character of not contending.
This is called employing the ability of the people.
This is called matching the utmost ancient of heaven.

Chinese direct to English (with synomyms):
good (perfect, kind, adept in) do (act, act as, serve as) bachelor (scholar, noncommissioned officer) not military (valiant, fierce).
good (perfect, kind, adept in) war (warfare, battle, fight) not (anger, rage, fury).
good (perfect, kind, adept in) victory (be equal to, can bear) enemy (oppose, match, equal) not take part in.
good (perfect, kind, adept in) use (employ, apply) people do (act, act as, serve as) of below (down; under; lower; inferior).
this say (call, name, meaning, sense) not contend (vie, strive, argue, dispute) of virtue (moral character, heart, mind, kindness).
this say (call, name, meaning, sense) use (employ, apply) people of power (strength, ability).
this say (call, name, meaning, sense) join in marriage (mix, match) heaven ancient (age-old) of extreme (pole, utmost).

(1) Although, looking deeper, I see insecurity and fear as the real source of anger and its cousin need.