yesterday was my 1st karate class...and i'm outa shape ever since i stopped exercising during the summer .. my instructor made me do a lot of pushups sit-ups crunches n all that stuff. the thing is that after 15 seconds of doing all those exercises i get so tired that i cant even continue or else i feel like my stomach is going to explode..(im 15 if that helps) what do i do to stop feeling like this its horrible please help ((