(a re-post of something I wrote in 2015)
God wants us to be "doers" of His Word. One of the main reasons this is so important is because there are many times when we can change and shape our circumstances.
Genesis 1:28 tells us to "Be fruitful, and multiply, and replenish the earth, and subdue it..."
If we're not doers of the word, being obedient to what God tells us in Genesis 1:28, our environments will subdue and have dominion over us.