I think "refuse to lose" is not just about confidence combined with ability. Rather it is "never say die" and never quit mentality. It is essentially an approach that says we are going to give every ounce of strength and effort on every play until we win. It is a bunch of very good football players, playing their very best, as a team, with one goal in mind - winning every game. Football is a game of guts, determination, will power, desire and effort. Assuming relatively comparable athletic ability (speed, quickness, agility, strength, execution, strategy, etc.), the team that wants to win the most usually does. It is that 'want to' mindset. You have to care deeply and give everything you've got. No half hearted efforts and never taking a play or two off. You run and hit hard EVERY PLAY until the whistle blows and you play within the rules and in accord with the coaching and each player does HIS job as close to perfection as possible.
To have the right attitude, players have to truly, madly deeply CARE about the results. It should hurt to let any of your teammates down by NOT excelling in your role on the team - whether it be as long snapper, QB, third string IB, scout team water boy, or whatever. Every member must excell. It is that simple.