I've been running for a few years now, I took a break over the holidays and just started up again. I started getting a sore left knee afterwards, and it got to the point where I couldn't finish my usual route. It dawned on me that I might have strained it over christmas moving a very heavy (of all things) treadmill down a few flights of steps. I remember resting it on my bent knee, step by step, although I did not feel any pain during the move. It's been about 3 weeks since then, is there anything else I can do besides rest? And for how long? Today I jogged for perhaps 3 miles before any discomfort set in. Any suggestions?