At some point you will feel down if your like me. Sometimes it appears like there is no reason, or maybe something bad actually happens. Something that has worked really well for me is something I learned from Tony Robbins.
Your physiology is closely connected to your emotions. This is easy to see: when you are feeling great how do you act? You do you stand? Or talk or move? Conversely, when you are down, how do you move your body? Your emotions control how you move, right? Well what if it also works the other way? What if you can control your emotions by how you move your body?
So try this right now. Note how you feel, and note how you are moving your body. Then listen\watch these three songs. When you are done, note how you feel and how you are moving your body.
http://youtube.com/watch?v=s9qvCTdBLDshttp://youtube.com/watch?v=N6j475XI1Xghttp://youtube.com/watch?v=Fki7agpULSYRinse and repeat if necessary. Other things that may help are to play DDR, jump on a tramploline, walk or jog.
If you make it through the three songs without dancing even a little bit, you win. You are hopeless.