Your mental game needs a solid foundation. That is formed from sound knowledge and effective skill. The context requires knowing, first of all, what is needed to play the game within yourself, understanding how the golf swing works, and how to put the two together in balance.
Unless you know your own, very individual, unique makeup, you will not know if you are, or are not, really playing the game within yourself. If you do not understand the basic movements and functions in your swing, you will not know if and when you are doing it correctly.
Of course, you can simply depend on other people to provide such basics for you and keep tapping their resevoirs so long as your umbilical cord will stretch. Or you can match the eloquence of this solitary game by learning to be an efficient, effective self manager. After all, it is you, by yourself, out there on the course.
No one truly can be self-sufficient without the knowledge that fits what is taking place and the skill that completes the task. An enormous benefit from those two concerns is confidence. If you have those two basics in good shape there is no way NOT to have confidence. But if either one of them is defective, there will be plenty of doubt.
The only point in a beginner's mental game is found in two things: focus of attention and willingness to learn. There is very little point in undertaking further sound mental practices until you begin to acquire necessary knowledge and skill. That's why we refer to a foundation. It's not likely that one would buy four wheels and forget the car. (Well, at least most folks would pause over that issue).
If you don't understand your own behaviors, how could you know if your way of thinking, feeling and acting was in sync or out of sync? If you are in sync, it will affect you positively. Out of sync "grabs you in the negatives." Now what does one do if there is no map that provides that important information?
First, get yourself profiled. No, not a golf profile - a YOU profile. We cannot fit ourselves to the game. We have to fit the game to ourselves. Learn about yourself and play the game in the style that Mother Nature gave you, not some style that is manufactured out of paper dolls from other peoples' games. Everyone is different. No two exactly alike - similar, perhaps, but no clones.
Then get your swing basics in line. Learn what "on plane" means and how you accomplish that with your grip and set-up. Learn how the swing maintains a motion that will bring the club-head back to the ball properly each time. Learn what it means to maintain the interrelationship in all the moving parts in your swing during execution.
Without all that, your mind is apt to wander, flinch, cringe or fight and your emotions will likely shake, rattle and roll (with apologies to Bill Haley). If you get those things together, however, you will be ready for the next level of learning and be able to go there with a solid foundation. Try that with a bandaid