My best advice is to not try to do everything perfect right away.

Try eating at McDonald's 1 less time a week for a month, then 2 less times the next month. Going cold turkey is just too tough, it's much easier to slowly eat away at your bad habits. If you love soda that much, start drinking diet. At first I hated diet soda, but honestly, drinking regular soda is horrible tasting to me now. After your good with drinking diet soda, try substituting a soda for a water every so often. Again, it's the little things that crush your diet.

As far as working out, all you need to do at first is elevate your heart rate for 20 minutes, 3 times a week and you'll start to get in better shape. Then build from there.

Baby steps.