I came across an interesting theory and I want to put it into practice to see if it can work...
any frame of mind you're in, generally it's imagined. whatever it is that you're thinking about that has you in a bad mood is already in the past, you're not actually experiencing it right that minute - you're imagining it and re-living it.
so why not re-live the times that you felt most inspired, most dynamic, excited, happy and energetic? tap into those memories and feel that way any time you want to... that's the theory anyway.
the suggestion is to write down three instances in which you recall feeling that state and for each, do something distinctive with your body while recalling each.
for example, recall the event that made you feel powerful and excited and then breathe out with your lips puckered (or whatever you choose). then your mind-body creates that muscle memory to access that connection.
then when you get good at that, trying doing it in the middle of a lot of distraction (which is the real challenge and more like life) - like in traffic or at a hectic day at the office.
it might help to keep a personal journal of the past experiences you're working with to really try to tap into those memories.
hey, who knows, it might work... I'm curious :)