your too extreme with your question answers... I didn't say your light jogging was useless, I dont know where you got that from. I was giving you some other options... fast pace walking is not a joke, I do that on a treadmill to preserve my lean mass...
You said how long for cardio, well it depends on the activity... aerobic excersice, tread mill, stationary bike, just sustain an elevated heart rate for 15-30 minuets depending on your body fat. When jogging your weight will give you some resistance, hence resistance training... So use distance as your gage, distance being the weight equal... I dont believe you should be jogging for 30 mins. Jogging having a close effect as sprinting you should try and close the distance with a shorter time, say Ex. 6-8 mins per mile for 2miles more than that and you might get into a catabolic effect.( when using this term you should understand we go in and out of catabolism daily, the key is not to stay it a catabolic situation.) You can avoid this effect by utilizing amino acids before and after your jogs...

For more specific data for you personally your gonna need some bodily stats... didn't mean to offend you bro...