Putting your muscles under constant stress leads to soreness and can raise your stress levels. It doesn't make sense does it? However, as you tear your muscles for growth your body will draw resources and you will feel a little sore and tired. To counter this, while still improving your fitness level, you can engage in yoga and stress reduction at the same time! These type of routines are great a few hours before sleeping to settle you down and get the blood moving freely throughout your body!