Not sure how much I can run. I stopped due to a f'ed up knee and I'm afraid it might come back if I do it again. Lasts for a week if returns.
oh ye running is awful for knees, don't then. weightlifting, even only body weight.
You can change running for knee up to the chest, aerobic type of exercises. It's not so effective but it's way less impact, and so, a good substitute when you can't run - either because of overweight or injury.