Here’s a quick (and very basic) refresher for anyone not solid on the difference between active and passive voice.
There are those who will tell you that any sentence using ‘was’, ‘had’, or ‘were’ is passive voice. This isn’t true. I’ve also heard people ignorantly claim that having your character simply sit in a chair and do nothing is passive voice. When referring to grammar, passive does not refer to the dictionary definition of the word (not participating, inert or quiescent). It refers to a specific sentence structure. ‘The kids were in the car’ is not passive, nor is having your character lay in bed all day.
In an active sentence, the subject of the sentence is performing an action. In a passive sentence, the subject is being acted upon.
Here are some active sentences:
Susan (subject) wrote (action) a thank-you note (object).
He (subject) picked up (action) a pencil (object).
Scientists (subject) discovered (action) a cure for cancer (object).
The emphasis here is placed on the subject performing the action.
Here are the same sentences in passive voice.
A thank-you note (subject) was written (action) by Susan (object).
A pencil (subject) was picked up (action).
A cure for cancer (subject) was discovered (action).
The emphasis here is on the subject being acted upon. In the last two sentences, the object (or the agent performing the action) is omitted altogether.
It’s important to remember that active voice is not necessarily “better” than passive voice. In basic college-level english, students are firmly encouraged to use only active voice. This is because for purely informational purposes, clarity is often more easily preserved in active voice. However, in creative writing, passive voice can be a very useful tool if you handle it wisely.
A more thorough explanation of passive and active voice: http://grammar.ccc.commnet.edu/grammar/passive.htm