Moods are a bitch.
Especially when you can't hold on to that excited feeling and the present moment gets you down again.
The biggest frustration is that change often doesn't come soon enough. You work on something, but you realise you're still in the same slum. And you think you can't really be happy until you've reached a certain goal. That brings a lot of mind induced stress.
I feel if I would balance my happiness, and spread it out a bit more so that it doesn't come in huge peaks and deep crashes, but more of a steady constant feeling, it would help tremendously. I'm working on that and already seeing improvement. Cutting down on the mood-swinging substance called coffee helped a lot to me, as well as meditating and accepting and being in the present moment without the constant anxiety thoughts.