Carbon monoxide poisoning question?

Obviously, I'm not suicidal or anything bullshit like that. But like, my family left their car on in the garage and its winter and we just found it running. So they opened the garage door and everything, but what are the possibilities of still dying from carbon monoxide from something stupid like that? And is it painful ? Will I just fall asleep and like die ? BECAUSE IM NOT TRYING TO, i just need to know. And if I feel all headachey should I just run outside for a little? Because, btw its -30 so it'd be pretty hard to do that. And its like a sunday night and i have ******* exams tomorrow.