HOW TO COMPLETELY FLATTEN YOUR BELLY IN 3 WEEKS?

I'm the same age and I have the same problem! (though I went to puerto Rico already during spring break, it's beautiful) so this week every day I have been doing 30 sit ups, gradually working up to 50 every few days. I already feel my abs toning and I've had a noticeably flat(ter) tummy in 2 wks. Gooood luck (: