Not so long ago, neuroscientists knew for a fact that once you were full grown you could not grow new brain cells. It turns out that was wrong. It is now an axiom of science that brain can be changed. This is called neuroplasticity. Not only can the brain be changed. It can be changed by our experiences, thoughts and behaviors. There is well known concept that : Nerves that fire together wire together! The opposite is also true: nerves that do not fire together unwire from each other.
What does this have to do with you? If you have a habitual pattern of thinking or acting, one of the reasons it is hard to break that habit is because there are nerves connections in your brain that have wired together. If you are trying to create a new pattern the new pattern does not yet have a brain based wiring.
When we are trying to do something new, it is usually not comfortable. The mistake we make is that since it is not comfortable we tend to stop doing the new behavior. We stop before the nerves wire together.
Also. over time, the nerve patterns that supported the old habits unwire and the old pattern will seem uncomfortable.
What is the moral of this story? Do not allow comfort to be your guide when you are trying something new. Even if you are not comfortable, when you engage in new behavior your brain cells that are responsible for that behavior are firing together. Over time they will wire together and you will then be more comfortable.
You might check out the book The Brain That Changed Itself by Norman Doidge. It is a great read.