If you can make one heap of all your winnings And risk it on one turn of pitch-and-toss, And lose, and start again at your beginnings, And never breathe a word about your loss:
The theme of loss (symbolized by the word "broken" in the last stanza) continues in this poem's third stanza.
This time our speaker counsels his listener about money, in particular about how to handle things if he loses it all.
If the listener can put all his money ("winnings") in a giant heap (maybe like this) and gamble it all away, but then start over and never tell anybody…
You know the drill at this point.
Clearly, we're talking about gambling here—well, sort of. Yeah "winnings" and "pitch-and-toss" are totally gambling words, but gambling is here a metaphor, for the most part. It's a metaphor for earning money and losing it by taking chances, by gambling (but not at a casino or something).
Speaking of pitch-and-toss: it's an old game where a group of people throw coins at a wall. Whoever's coin lands closest without touching the wall wins all the other coins. There are other versions of the game, but that's the most common.
So what's the point? Earn, take chances, lose, be quiet and strong about it, and move on—that's what being awesome is all about.
Whining and crying about your losses? That's decidedly not awesome.
If you can force your heart and nerve and sinew To serve your turn long after they are gone, And so hold on when there is nothing in you Except the Will which says to them: "Hold on!"
If the speaker's listener can force his body to keep pushing further, even when it is worn out and tired, even when he feels like he has nothing left except the will to "hold on," then…
"Heart and nerve and sinew"—those are pretty biological terms now, aren't they? Is the speaker writing a textbook, or trying to show off that he knows cool words like "sinew"?
Well, what we know for sure is that "sinew" is a fancy term for a tendon or ligament.
"Heart and nerve and sinew" here is a classic example of synechdoche. These three words are the speaker's way of saying "muscles" or "body," but in a way that calls attention to the actual, physical components of motion: nerves and sinews.
Now the stuff about "serve your turn" is a way of saying "do things on your behalf" or "do what you want them to do."
The body gets tired and worn out. This is what "long after they are gone means."
Obviously the heart and nerves and sinews aren't gonna literally go anywhere (so this is a metaphor), but if they get tired and worn out, they might as well be "gone."
Even if those nerves and sinews are totally exhausted and worn out, one thing still remains: the will to go on.
The will is some type of internal desire or motivation. It's so powerful, the speaker implies, that it can force those worn-out muscles to hold on and keep going.
We're not joking. The Will here (note that it's capitalized in the poem, showing its super-importance) is like some invisible power that is so strong, it can make things move—like muscles.
This whole passage is about the power of that Will. Even when the body seems like it is beaten and can do no more, the will can make it do more. The will—the internal spirit—is stronger than the body.
We can't help noticing that these lines remind us of another very famous Victorian poem: Tennyson's "Ulysses".
That poem is also about striving and fighting on, as in the poem's concluding lines: "Made weak by time and fate, but strong in will / To strive, to seek, to find, and not to yield" (just thought we'd share).