I started out slow, walking 2-3 miles, 4-5x/week. Then after six months, I began mixing in jogging in 2-3 minute spurts. By that time, I had lost over 50 lbs. (I also eliminated sodas and most other drinks besides water from my diet and I ate less fried/junk foods).

If this will serve as encouragement, according to the Strava app I use when I run races, I burned over 3200 calories yesterday during the half marathon. That's almost a pound of flesh (and I did lose, despite drinking 2-3 liters of sports drinks, almost 6 lbs. of water weight) gone in a day (granted, I splurged and ate almost 5000 calories afterward, but I don't do this frequently at all after long races/training sessions).