...The fourth thing is, with the proper preparation, no matter how difficult something seems, you can master it through continued and repeated efforts--

Nope, 'taint true. As a singer who has tried hard to get even marginally efficient with the guitar for the past 30 years, I can tell you that it ain't so.

Some things come easy to me, singing, mathematics and engineering are fine. Guitar playing NO, continued and repeated efforts only serve to prove that I was never intended to be a guitar player. The twelfth root of two was fairly simple to derive myself one time when I needed to find out fret spacing, but hearing chords and intervals just doesn't happen.