Without a doubt, a run does give you an amazing feeling of achievement, and I say well done on your effort. However I'd be less than honest with you if I didn't also share with you few facts. You are running to lose excess weight. That excess weight, when combined with a vigorous activity such as running, ends up placing a tremendous amount of stress on your tender joints. Sure, our connective tissues are extremely powerful, and are designed to withstand a high level of stress, under normal and ideal circumstances, neither of which you're in possession of right now.
Without beating around the bush, to lose weight, the initial weight, it would be advisable to do it under less stressful environment as far as your joints are concerned. So an exercise like stationary bike, or rowing machine, or anything that does not produce that jarring effect running does or has on your lower back, ankle, and knee joints, would be the most ideal at this point in time. To encourage you on what you're currently doing, (not to mention enjoying), and remain silent on sharing what I know and what I've just shared with you, would be less than honest Sir.
Thank you mate.