That moment, right after being knocked down, before you marshal your energies and get back up to fight on.
Difficulties and confidence: On a superficial consideration, they might seem to be inversely related - the more you have of one, the less you'll have of the other. But allow me to quote one of my favorite philosophers, the prominent first century Roman lawyer, and advisor to very successful people, Seneca. These are his thoughts, in my own translation from The Stoic Art of Living:
"The powers we have can never inspire in us a genuine inner self-confidence until we have confronted many difficulties along the way, and even now and then have had to struggle fiercely with them. This is the only way our true spirit can ever really be tested - the inner spirit we have that will never consent to be ruled by outer forces. The nature of such a spirit can be seen in the fact that no prizefighter can go into a contest with high spirits if he has never been beaten black and blue. The only man who can enter the ring with confidence is one who has seen his own blood, had felt his teeth rattled by an opponent's fist, has been tripped up and has experienced the full force of an adversary's charge, who has been knocked down in body, but not in spirit - one who, as often as he falls, gets up again with greater determination than ever." (Epistulae Morales, I.75)
In another place, Seneca goes so far as to say:
"Disaster is virtue's opportunity."
Disaster. Catastrophe. Failure. Disappointment. It's all about how we react to difficulties. Do they weaken us and take us down, or strengthen us and build us up? To an amazing extent, and within an extraordinarily wide range of circumstances, that's largely up to us. And in responding well to the trouble we face in our own lives, we can be an example to others of what it's like to be knocked down, but not knocked out.