Before Exercising, be sure to properly stretch all muscle groups
I went running today, and I forgot to stretch out my calves, and boy am I paying for it. On one hand, they are rock hard, which is good, on teh other hand they feel like they are on FIRE! Ouch! And then, when I went to get icepacks for them, I opened the freezer, bent down and got them and hit my head on the refrigerator handle (the freezer and fridge are tall and side-by-side). Hurt like a bioch!
Good story huh? Moral: Make sure you properly prepare, no matter how harmless an acticity may be.