Konichiwa said it perfectly. To project, sing, or do ANYTHING vocal, all of the energy must come from the stomach.
In addition to what konichiwa suggested, also try this: Stand straight up and let your gut hang out. No sucking it in, to pushing it out. Just stand up like the fat person you are and let the gut hang. Now, move to a mirror. While standing in your fattened position and looking in the mirror, take the deepest breath you ever thought possible, but MAKE SURE YOU DO NOT MOVE YOU SHOULDER, CHEST, NECK, OR HEAD. Right where you feel you stomach stretching, thats where the power comes from.