When I first started writing, I was what you might call an organic writer. I did everything according to instinct, with very little formal training in . . . well, anything at all, really. I'm still very much that way. I write according to my gut. My guts are very overworked, overburdened, and overtaxed, but hey, that's the way I write. That's where the passion comes from.
But being untrained as I was, I made a lot of booboos. You know all those things they tell you not to do? I was doing them. A lot.
Now that I'm sooooo much older and wiser and all that, and have taken writing classes and listened to what my peers and my critics are telling me, I'm more aware of my failings and have spent a lot of time over the last year correcting those failings. One of those failings is my tendency to use the passive voice.
So, what's that? I always thought it had to do with passive aggressive, you know -- you just take it and take it and take it until someday you strangle someone. Or sabotage them behind their backs, all the while looking like sweetness and light. Well, while that's awfully fun and leads to some great novel ideas, that's not what it means.
Check this out:
1. She was sitting on the porch.
She sat on the porch.
The first sentence is passive. The second sentence is not.
2. He had been wishing for a pony for Christmas.
He wished for a pony for Christmas.
Again, the first sentence is passive.
I'm now going to very organically, without any formal training, explain why we don't want passive.
You notice, with both those two passive sentences, that the reader is a step removed from the action. It's like a comfy barrier has been put up between them and the character. By taking the passive voice out and putting the reader front and center in the action, they can partake of the emotions and the undercurrents of the story more completely, becoming part of it rather than looking at it through a window.
Additionally, by taking out the "was" and the "had been," you're tightening up your writing, making it crisper and cleaner.
There are times when you'll want "was" and "had been" and their brothers and sisters -- that's when you're writing in past tense, such as in expository narrative. But I do hope you're not using a lot of that -- show us, don't tell us.