"You exercise...right?  Do you ever get sore the next day after a hard workout? 

It's probably from something called lactic acid.  Lactic acid gets built up in the muscles after exercise and causes the muscles to be sore.  Some great ways to help stop or diminish this soreness are:

1.  Drink lots of water after work out especially with electrolytes (not Gatorade)

2.  Take an Epsom salt bath.  Epsom salts are magnesium sulfate and this helps to
      relax the muscles and work out the lactic acid.

3.  Stretch!!!  Especially right after workout and the day after the workout. 

4.  Massage your muscles after stretching to push out the lactic acid.

5.  Do a lighter workout to help push out the lactic acid.

As the muscle fibers grow and become more efficient taking in oxygen, the lactic acid will not get built up as much which will lessen your soreness.

The end of the year is coming and so are all those resolutions to lose weight and get fit.  Start now and get ahead of everyone!!"