Your mind is more than just a 'brain'.
Your mind is powerful enough to greatly affect your body and health (for better or worse) just by thinking a certain way. This effect has many observable results from people thinking themselves into becoming sick or even eventually dying, to incredible feats of strength or stamina. Our mind is a lot like a muscle in that it can be 'exercised' and trained to perform better.
All you need are the tools to get your mind into shape!
Over time, by exercising your willpower and positive thinking both become stronger and easier for you to harness. Much like learning a new sport or task, what seems difficult (even impossible) at the beginning will slowly change to be possible, but challenging. Eventually with hard work, the task or activity is easy - at which point you have 'mastered' it. Of course your mind is more complicated than learning a new program or game, and made more so by the fact that you are the very thing you're trying to control! That being said, improvement works in the exact same way.
Work at it, keep trying no matter what setbacks occur - stay on course and you will get there!
You don't have to do this alone. In fact, trying to do everything on your own is often a recipe for disaster. We're only human, and we need to rely on each other for help with the things we struggle with. Would you try to fix every plumbing and electrical problem in your home? Every car problem? No, you reach out and ask an expert! And those same experts look for other experts when they need a new roof, or website or their driveway resealed. Taking on too much or too difficult a problem guarantees failure. You don't want to fail before you have a chance to start...