You can run, just eat appropriately for it and you'll be fine.Wouldn't mind doing the run 3miles challenge, actually have a treadmill in the back room that never gets used, and a cycle-machine IIRC.
Problem is I can't risk losing any more weight...
Go to the gym by bike instead of doing cardio at the gym. Win.gym is ~20 minutes away each way, so going to the gym costs me ~3h
~1,5h of using machines for upper body and legs