It may seem unfathomable that the thoughts you think can literally change your brain. However, neurotransmitters like dopamine serotonin, oxytocin. GABA, cortisol, and others are altered based upon our most consistent thought patterns.
For instance, if you consistently think thoughts like, “I can’t do this,” or “This is too hard,” or “I’m so depressed,” or “It’s such a crappy day,” etc. it may seem as though these are only cognitive choices. These little thoughts are indeed physiologically altering, though.
Thoughts like these will not boost your immune system, create more dopamine, known as the motivation molecule, or induce higher levels of serotonin and oxytocin which are known for making us feel happy, positive, and even improve our cognitive functioning. Uplifting, positive thoughts, indeed, do.
Your thoughts can literally cause you to be smarter, more fulfilled, and more eager to take on challenges that come up in your day, or tackle a challenging problem that then causes you to get a raise at work, or offers you an inventive new product that you can offer to the world as an entrepreneur. They can cause the grey matter in your brain to grow, and new neurons to develop so that you can write incredible songs and poetry or paint absolute masterpieces.
Your thoughts can also cause sickness, and even an early death by inducing anxiety, raising cortisol and adrenaline levels and inciting inflammatory cytokines that cause just about every disease we struggle within modern society.
While some researchers chalk this phenomenon up to the Placebo effect, and others are convinced that our consciousness directly impacts our DNA, our cell signaling pathways, and yes, even the neurotransmitters released in our brains, it doesn’t really matter how our thoughts are changing our physical health – -because they simply do. 
One of the many gifts of meditation is to help you gain control of your thoughts so that negative ones don’t run rampant in your mind, and thus alter your physiology in a negative way.
Meditation offers a silencing of what has been called the “base level” emotional state which is really nothing more than the inner critic roaming ceaselessly from topic to topic, and often with no positive direction.
Simply closing your eyes, and focusing on your breath gives your mind something to focus on, which begins to alter the baseline emotional state, and your ensuing physical and mental health.
Meditation also alters the hippocampus, the prefrontal cortex, and other key areas of the brain associated with memory, learning, attention, concentration, altruism, creativity, and other important cognitive functions. 
Meditation is one of the few ways to stop a habit of negative self-talk effectively and change it toward thinking that can not only fuel a positive worldview, but actually heal us when we are sick, and uplift us when we are sad.
If you want to silence your “inner critic” – that annoying voice that tells you that you aren’t good enough or that you can’t achieve anything you desire that is riddled with self-doubt, then try the following tips to change your thoughts, and thus change your brain:
- If you are a sensitive person, then ask yourself how you can take one step toward your goal that you KNOW you can achieve, and then take it. This will build an internal locus of control which is what positive psychologists call an inner belief that you can achieve anything you put your mind to.
- If you are a perfectionist, ask yourself how you can make something better, but withhold judgment. Don’t say to yourself, “This isn’t good enough.” Instead ask the question, “This is amazing but how can I make it even better.” This slight shift in thinking opens opportunities instead of building more self-doubt and a lack of confidence.
- If you catch yourself thinking limiting thoughts even though you want to think empowering ones, write down the limiting thoughts on a piece of paper, and then write down three reasons why you know it isn’t true. Seeing this in writing will have a profound effect on your inner belief, and thus the thoughts that you most consistently harbor.
- Meditate and just observe your thoughts as they arise – the good, the bad, the indifferent. Don’t get lost in any train of thought. Just label it as thinking. Let emotions or bodily sensations rise and fall away. This will help you to begin to differentiate yourself from your thoughts and empower you to then change them.
Your mind will always think, but you can control what you think more than you may realize. Take control of your thinking, and you’ll gain control of your mind, body and total experience. A more positive outlook will always reflect in your body and day-to-day circumstances.
 Benedetti, F., Carlino, E., & Pollo, A. (2010). How Placebos Change the Patient’s Brain. Neuropsychopharmacology, 36(1), 339-354. doi:10.1038/npp.2010.81