I have studied the violin since I was 5. I don't mean I have played the violin. I don't mean I have played the fiddle. I mean I have STUDIED the violin since I was 5. There's NO WAY I could tell you the total number of hours I have practiced in my life. Malcolm Gladwell wrote a book called "The Outliers: The Story of Success". In his book he looked at factors and common denominators with successful people, sports teams, etc. Throughout the book, he repeatedly mentions the "10,000-Hour Rule", claiming that the key to success in any field is, to a large extent, a matter of practicing a specific task for a total of around 10,000 hours.
TRUST ME. I HAVE PRACTICED WAY MORE THAN THAT.
I had periods of time when I was a child where I would practice 1-2 hours a day. Yeah, I know. Insane. . . .
But one thing I learned about practising. And one thing I learned about succeeding at a skill or achieving a milestone. SOMETIMES YOU HAVE TO WALK AWAY.
I noticed that I would reach a point where I would plateau - I would go over and over and over some passage in a piece I was working on and could not get it consistently to save my life. I would spend 1 hour just on a 16 measure section. Yeah, I know. Again - insane. . . .
But I learned that after that hour, if I just quit and walked away, the next day I could play it perfect. Every time.
A friend and I have been corresponding about some life issues she's dealing with. I think about my own personal patterns. I think about my own personal growth in life. I think about so many times where I have hit a plateau or where I have even felt like I took a huge leap backwards, only to give up for awhile and later end up in a much better and higher place.
If you feel like you are running into a wall over and over. Give up. Leave it alone. Give yourself space and time. Take a break. Walk away. Focus on something else for awhile. Odds are when (or if) you go back to it, it will be 100% better. And if not, I almost guarantee YOU will.