When I was about 12 years old, a friend of mine wanted to learn guitar. He took a few lessons from local guitar teachers but they discouraged him from continuing, say that he didn't have any talent. They didn't think they could teach him.
Luckily for my friend, one of the parents in our neighborhood was an amateur guitarist and volunteered to teach this kid, at no charge. So they started lessons. At first, this parent experienced the same thing that the "professional" guitar teachers had. My friend didn't pick up the concepts easily. He forgot where to place his fingers. He had difficulty understanding sharps and flats at first.
But this teacher was patient. He didn't give up, and neither did his new student.
My friend gradually mastered the basic techniques of strumming and playing chords. And that's when it really started. His appetite for guitar became insatiable. He brought his guitar to school to jam with the other guitarists in the music room during free periods. We formed a rock band, with me on keyboards. I remember going over to his house one day and seeing sheets of paper spread out all over his room, where he was listening to records and trying to figure out the chord progressions to one song after another.
Slowly, and I do mean s-l-o-w-l-y, he got it.
Even though his focus was rock, my friend eventually spent a few years studying with the great jazz guitar teacher Sal Salvador, because Sal taught his students how to know the whole fretboard in a complete way. My friend also took music theory classes in school and made every effort to learn more about music. He kept jamming with other musicians and basically lived and breathed music.
This "kid," whose first guitar teachers gave up on him, eventually grew up to become a professional musician. He built a home recording studio and has shared the stage with many rock legends.