You have two kinds of style: surface and deep.
If I could see you sitting there reading this column, I would have an impression of your surface style from your features, hair and clothing. Over time I might get a sense of something more important: your deep style, or who you really are -- your values and character, the decisions you've made in life, the way you treat people.
Likewise with writing.
If you sent a message to me, I would have a sense of your surface style. I would know instantly whether you wrote in standard English, followed the rules of language and expressed your thoughts clearly. I would see whether your vocabulary was limited or broad and whether your sentence structure was simple or complex, monotonous or varied.
But I also would have a sense of your deep style -- not who you are exactly, but an impression of who you are. It would take only a few sentences to form this impression, but that impression, a sense of the person behind the words, would stay with me. It would linger long after I had forgotten the contents of your message.
Compare these two sentences:
"It is my recommendation that we make a change in our policy."
"I recommend we change our policy."
On the surface, the first sentence is characterized by a noun-heavy style, the second by a verb-activated style.
Now look beneath the surface. The first sentence leaves the reader with the impression of someone writing without authority or conviction. The second creates a sharply contrasting impression of someone who is decisive, emphatic, resolute.
Keeping in mind the same stylistic technique -- prefer action verbs to their noun equivalents (or nominalizations) -- compare these two sentences:
"We have a need to make a reduction in our expenses."
"We need to reduce our expenses."
Which surface style leaves you with the impression of decisive leadership?
The impression you create of yourself in your writing is sometimes called your persona, a concept that goes back to the masks worn by actors in the plays of ancient Greece. Your persona in writing isn't really you; it's the impression you create of yourself through your words.
When you write, you generally want to make a good impression, but ask yourself this: Are you as intelligent, knowledgeable and fair-minded in real life as the image of yourself you are trying to create? Perhaps not.
But don't feel guilty for being an imposter. Instead, try this approach: Use your persona to build yourself up. First, imagine yourself as the kind of person you'd like to be. Then try to project that image of yourself in your writing. I think John Steinbeck had something like this in mind when he described one of his "big reasons" for becoming a writer:
"I instinctively recognized an opportunity to transcend some of my personal failings -- things about myself I didn't particularly like and wanted to change but didn't know how."
Use the persona you create in writing to become the person you'd like to be in real life.