What usually causes cars to break down? Driving 1,000 miles...?

Maybe I'm being paranoid but in 3 days, I'm driving fro Louisiana to north Carolina, a little over 1,000 miles and 18 hours. My car has never had any problems, I got the oil changed and all that. I'm just worried. Should I be alright? It's a 2006 mustang with no problems before.