One thing I think a lot of people forget is how much getting outside and moving your body can lift your mood. I sometimes forget myself and will be working inside all day and wonder why I feel tired and have low energy. I am not just talking about exercise, which of course is a big part of it, but really getting out into the fresh air, into nature to really and let yourself expand and clear that negative, stuffy energy.
When was the last time you did something playful outside like do a cartwheel (can you still do one?) I found I still have it in me to do them— even synchronized with my friend! If that is too much how about just walking through a park and really getting close to the trees and nature and paying attention to all that is around you.
Sunny or cloudy, its good to get out of that house, that office and walk around and move the body and the spirit. Think of being outside and all that space your energy has to expand up into the sky when you are walking and I promise your spirit will lift.