I know you're looking for it, the song played at the end of the Biggest Loser season 7 premiere. And I found it: It's called Courage Is by the band The Strange Familiar. Some of the lyrics:
Courage is when you’re afraid
But you keep on movin’ anyway
Courage is when you’re in pain
But you keep on livin’ anyway
We all have excuses why
Living in fear, something in us dies
Like a bird with broken wings
It’s not how high he flies, but the song he sings
Courage is when you’re afraid
But you keep on movin’ anyway
Courage is when you’re in pain
But you keep on livin’ anyway