I don't like Peebles approach at all. He has a valid point about the requirement for self discipline in order to better your technique, but music comes from the head not the hands or technique, so I don't think that necessarily correlates to a better ability at all.
For me personally I find the best motivator is tone and most important in improving your actual ability, which arguably as a musician, is way more important than technique, is developing a good ear. Seriously, if your tone sucks and is aggravating you just you just don't get muscially motivated and you don't get the melodies and licks flowing around your head, so it doesn't translate to the guitar. I'm not talking about ton of delay or effects, just a good guitar and a good amp and a confident deposition. If your ear sucks you'll never know what to play or what mood to set and it will always comes out like a lesson or a pile of directionless licks, scales and legato and your inspiration will be so low your ability will never improve. Also playing chords an improvising in time and with the beat is crucial in improving your ability. Especially tieing in your solos with the chords and playing solos and riffs on the beat.
I think you should check Milan Polak out. Much more Andy Timmons/Richie Kotzen style and way more fluid and useful as a teacher.
Just these 3 videos go a hell of a long way, he has some very simple advice that is groundbreaking.
http://www.youtube.com/watch?v=N2L3HYfcRBM
http://www.youtube.com/watch?v=2BeFoS3ipSY
http://www.youtube.com/watch?v=R7bdMrJcmKQ
Oh and this one for practicing your picking co ordination and left hand strength. lol.
http://www.youtube.com/watch?v=18kT34TVoNQ