Sorry to hear you are under the weather Sam, be careful not to over do it, trust me, I know.
Doing a lot of core strength exercises as prescribed by physio and started some light running, basically leading my wife through C25K program. Looking forward to a time when my body is fully functioning again!
I started my running outside, then tried using the treadmill when the weather was poor, and when I was working away. I have to admit I can barely stand it. There is so much missing as compared to being outside; fresh air, scenary, hills, wind, terrain, pace control. Get outside and run! Slowly increase you weekly mileage but don't overdo it pace-wise; 1 interval session a week is probably enough to start with, with the rest of your runs slow\easy pace. There are plenty more experienced than I to advise mind you. If you increase the mileage and don't change your current earing habits the weight should look after itself.