Passive voice feeds on all those words of “was”, “were”, “begin to”, “have been”, “had”, “almost” and the rest of their ilk that pepper through the narrative. And it kills the pace of your story, slowing the action, making your prose, gasp, boring.
Don’t despair if you fight this problem, you are not alone. I struggle with this foe myself, weeding the “was” from my prose often, sighing as the war rages on. However, there is hope, as most instances of passive voice can be rewritten and if it creeps in to your drafts, it can be edited out.
So, take your stand against the passive voice and show your readers, do not tell.
Elwin was drawing his bow and was aiming his arrows at the Chimera as fast as he could. He was firing them, but he could see he was not having much effect on the creature. His arrows were hitting the beast and the beast was screaming in pain, but it was not falling. The Chimera was still moving forward, it was still coming.
In rapid succession Elwin fired his arrows, each deadly projectile aimed at the heart of the Chimera. They hit their mark, blood drawn, but the beast still lumbered forward, screaming its pain, still coming for Elwin.
Now both examples narrate the same story, but the pace, the flow is different in each paragraph. Remember, the best way to describe a scene is not to tell it to your readers detail by detail, but to show it through well chosen descriptive words.
Good writing gives the reader what they need to form a picture, to inspire the imagination. It does not read like a step-by-step instruction manual.