Seven years ago this month, trailing in the polls with two months until the Iowa Caucuses, then-Sen. Barack Obama gave the speech of his political life.
(Gets especially good around the 15:00 mark. Which is also technically when the speech was supposed to end, but that wasn't going to happen.)
If the delivery seems uncharacteristically rough, note that this was the first time most of those lines had ever been delivered. It would be far from the last. In the room at the time, our minds were being blown repeatedly.