Running: Go running four to five times a week for about 30-45 minutes. As you get better increase your running time. Running burns the fat. It doesn't matter how many pushups you do, they will just burn calories unless you run.
Pushups: Do about 100-150 pushups three to four times a week. This will really help you get in shape if you do this for about a month. Do about 15, take a short break, do another 15, take another short break, etc.
Sit-ups: Sit-ups help you work our abdominal muscles and get you a six-pack. Do about 100-200 sit-ups five to six times a week.
If you have a gym nearby go there and work with the weights. Play music that will get you pumped and make you work harder.
