While it's important to let each emotion go, sometimes they cling a little harder; linger a little longer; dig a little deeper. In times like that, it's important not to add emotions to emotions. For example, getting angry over being sad is certainly not going to make you happy, now will it?
Yet there are circumstances that are bigger than your day-to-day feelings; where you can't just 'get over it'. In those times, don't force anything. By all means, do stuff that brings you good feelings, but don't get stuck on being stuck.
Let it be... this too will pass, when you let it runs its course.
It's all part of being human.
Keep the light on!