While the Backstory of characters in a writer's head can really help to deepen the narrative (i.e. gives the reader more understanding of where the characters come from and the motivations behind some of their actions), it can also slow down the pace of the unfolding story and halt the action.
As a writer, do you ever find that you are dumping a lot of Backstory into the first few chapters of your writing? Do you feel it is necessary to get all of this information out so that your readers will understand your character better? Is there any way to hold off on plugging in all of this Backstory . . . can you disperse it throughout your book or short story? And what parts of the Backstory are absolutely essential?
For example a piece of writing may start like this:
Sonya screamed at the oncoming car that was about to hit her. She had only been shopping for groceries for her ill grandmother. Her grandmother was her very best friend in the world. She had lived with her grandmother since she was six years old because her mother and father had died in a car crash. Sonya and her grandmother did everything together--planted flowers in the garden, listened to the radio together, baked. In fact, Sonya had been shopping for flour at the grocery store because she wanted to bake her ill grandmother a batch of the hazelnut cookies she loved . . . (etc, etc).
In the above example, is it really essential that the reader know everything about Sonya's relationship with her grandmother, at least at this point? The Backstory stunts the action which is Sonya facing her death at an oncoming vehicle. On the other hand, based on this example, are there any key elements of Sonya's Backstory you can see that might be worth revealing in the opening paragraph?
How do you handle Backstory in your writing?