fitness training tips exercises?

ok so my holidays are coming up soon we get 6 weeks off and in that time i wanna get into shape. it dose not have to be some miracle shake or anything easy just exercises that work and do a damn good job. my reason: i have only got 7 months of school left and out of the three years i have known this girl i havn't been able to talk to her or even at least say hi too i'm hoping getting fitter will boost my confidence and open my social life a bit more im tired of being the quiet kid so ive got that motivation behind me but yet everytime i do sets of situps my mind is always wondering why bother it not having any affect nor any pain.. so any motivation thoughts that help u that u use please share.once again i will mention that i know that me getting fitter won't exactly make her fall in love with me or any crap like that all im out to do is be more social and have more confidence behind and the fact if i don't talk to her i will regret it for a long time...it may sound weird but its the way i work