i ran, or rather lightly-jogged, a few hundred meters today...had to stop as got some mad pain in me calves...ye gods it's been so many beards since i last played football, wouldn't last 5 minutes now.
When was the last time you excericsed mate ?.
That pain is your calf muscles tightening ( your bodies way of telling you to stop ). Next is a strain or tendonitus / achillies problems.
If you haven't done anything for ages, the first few weeks should be a load of stretching before and then a jog at just above walking pace on flat ground for about ten mins just to get your muscles used to running again.
I know this as I didn't do a thing for four years and then started again too quickly a few months ago - spent weeks with calf sprains and tendonitus !