Emotions are everywhere, there is no way to escape them. From the very happy cashier to the very upset man next to you in traffic, from the time you wake up till the time you go to rest – even in your sleep, while having some very emotionally charged dreams. So, if emotions are all around you, why wouldn’t they be part of your writing?
When writing a piece, pay special attention to the emotions of the characters. Emotions should match the situation, and the character type. It would be weird to have a character that just suffered a heartbreaking loss, be worried about triviality (just to continue the story) – unless it is done on purpose to stress the unusual personality of this character or the particular way to cope with trauma. Such is the case of the serial killer experiencing ecstasy while murdering someone. It is all a balancing act. When you balance emotions in a piece of writing, it helps the natural flow of the story.
The question is, can you use emotion to dictate the story? Some pieces of flash fiction are a very good example of this. It starts with an emotion and the emotion develops the story to the end. Do a little experiment; when writing your next piece, pay special attention to what the characters are feeling and see how it is relating to the flow of the story.