I read this term years ago from Frank from the "V" and it that context was used in describing a professional look and demeanor in cycling. It has a kind of gravitas and toughness. I like the term.
Control
Calm
Cool
Collected
Confident
Think of any Clint Eastwood movie.
Being stoic in victory or defeat. Pouting is for children. Exuberant victory dances make you look as if you rarely win. Behave as if winning is something you do often. Even it is your first win, act like it's old hat.
If you do, be deliberate in engaging with others and use words with exactness.
Some I follow on twitter who I think are good at being casually deliberate are @tannerguzy @GeorgeBruno @BillyRedHorse
It is no coincidence these gentlemen are devoted aesthetes.
Be well trained for physical competitions.
For other endeavors I recommend an old alchemy motto, "read, read, read, work, pray, reread." And my derivative, "Write, write, write, read, rewrite."
Faking it can only take you so far.
It is about avoidance of things that your ego won't abide, rather than the performance of activities that feed it.