He whose only tool is a hammer, sees everything as a nail. -- Abraham Maslow
The person whose only tool is a hammer is very good with it. The confidence they have and the competence they exhibit comes from hammer experience. If they have been hammering at stuff for a long time they know exactly where to strike, with how much pressure or force, to achieve the desired results. They are one with the hammer. I know a guy who claims he can fix anything with duct tape, a phillips screwdriver and a ball-peen hammer. No, he's not a red-neck.
Confidence comes from competence. Competence comes from experience. Experience with a wide variety of tools, allows me to know which tool to use in which situations to achieve a specific desired result. I even know how to use multiple tools to achieve the desired result. But first, I have to know what result I want before I decide what tools I use, knowing the whole experience is doable.
The Four Levels of Competency are attributed to Abraham Maslow. Let's walk through them briefly.
The Unconscious Incompetent: Here we have a person who wants to do something or to be something and is just beginning. They are clueless when it comes to the tools, the projects, and the desired results. Let them use the wrong tool and they can be dangerous. Give them any unfamiliar tool and can you say "disaster."
The Conscious Incompetent: Experience includes mistakes, many mistakes, and some successes, moderate, exciting successes. The one who blithely swings a tool around because they have it, if they are watching what they are doing, will see the damage and learn control. They have just enough experience to know how dangerous they are, and are at the beginning, the teachable moment, of learning what they can do, and not do, with what they have. Experience is the best teacher (I heard that somewhere).
The Conscious Competent: After long experience, the hard apprenticeship under a knowledgeable teacher, our learner has come to know what tools are available and what can be done with each. Every action becomes thoughtful and deliberate, and confident. There are no surprises but a calm acknowledgment of the end results. Now, beyond the apprentice stage, they use their creativity with their knowledge to do more than they thought possible.
The Unconscious Competent: Have you ever seen someone so good at what they do it looks like they are playing? I'm not talking about the person who has done the same thing so many times it is done by rote, with no thinking or feeling. This person is stuck in a rut and can't get out. But those where there is an enjoyment in knowing (intimately) the tools, in seeing (without being able to explain) the end results long before the accomplishment of those results, in finishing and knowing the excellence of the work.
These people aren't one with the tool, they are one with themselves.