Yesterday I was in the gym and wanted to do a workout oh so badly! But my body was not having it. So after a warmup I decided to concentrate on body work (stretching, rolling on a lacrosse ball, and foam rolling). It was much needed and I recommend at least once a week to any person exercising at least 2-3 times per week!! You will be surprised how it helps. So if you walk into the gym one day and your body is saying "No", listen to it and take the day off. It wont kill you I promise....
If you are feeling crappy still after a day of repair then check your sleep patterns! I, for one, am very guilty of a BAD sleep pattern!! I never get consistent sleep and now my body is paying for it because I feel like a congested sack of rocks!! If you want a couple tips to set a routine for a healthy sleeping habit click http://marksdailyapple.com/insomnia-sleep-tips/.
So again listen to your body and save yourself from injury, depression, and lack of mental clarity!!