i can't sweat that
That’s not even a challenge to me. I’ve had worse. I’ve got bigger things to worry about.
You said you'd never beat me in a video game. Now you beat me. I can’t sweat that.
He said he'd never beat me in a race. Now he's beating me. I can’t sweat that.
She said she'd never beat me in a drawing contest. Now she's beating me. I can’t sweat that.