My lower back aches whenever I do basic activities. Today I got some rubber mats for my gym, I was laying them out and 15 minutes later my back is killing me. I tried shoveling snow last week, forget about it. I could only stay hunched over for 5 seconds at a time after about 5 minutes of work. It's not really a "pain", just the muscles that run along my spine are exhausted/aching at my lower back. I do deadlifts regulary, so I don't believe the muscles there are particulary weak. Does anybody else suffer from this?