There are, in my opinion, 2 types of soreness. The first is from exercise, and the remedy is rest. The second is from stiffening, and that requires exercise. How do you determine the difference? Experience. Here are a couple of examples:
I ran last Sunday for the first time in 3 weeks and my shins are sore. This is a result of mild deconditioning and I am resting for 6 days, with a plan to run again on Sunday. I will slowly rebuild conditioning with increased frequency and distance. Example 1.
Quite often I experience lower back ache and I know I need to stretch out and loosen up. I use a program of targeted dynamic stretching, followed by the stationary bike which loosens my back like nothing else (!), then a static stretching cool, down. Example 2.
So the next time you feel stiff or sore, ask yourself "What KIND of sore is this?" You may be resting unnecessarily and exasperating your aches, or you may be overtraining with the same results.