I was just told id be pretty id lose weight..now what?

Ok. Heres the deal. and you can either be serious when answering this or you can be a jack. I weigh about 245 lbs right now. I was just told by someone i know that i would be really hot if i was skinny, but that no guy worth my time is gonna look at me twice if im not. Which i have found to be fairly accurate. I want to lost weight as fast as i can, with as little damage to my body. I dont have any money for a gym membership, so i dont know how to get exercise in when itsw so cold and snowy. but... if some one has ideas. PLEASE! I want to be pretty. I want to be hot. I want boys to want me.