Thank you. I fully agree with all of the points you have made. In addition, I have found I can try too hard at times. When I am getting tired and practice too much my playing gets worse instead of better. I need to take a break in order to progress. Trying too hard causes a tension that is counterproductive, especially to learning good vibrato. There were many things that contributed to my quitting when I was young. Tension, pressure, trying too hard and being in too big of a hurry was a big factor. I lost the enjoyment of the music.