If you've met me you would know that I'm pretty much skin and bones at 6'1" and 140lbs. Gaining muscle has always been difficult and physical training an uphill battle. In my search for the best approach efficiency (read: maximum results through minimum work) had to be number one. I stumbled upon this interview a long time ago, but have recently spent time studying it carefully for physical fitness.
A lot of us think of "working out" as something that would be nice to do, maybe something we should do, but is ultimately too much work. The term, "work out" suggests that you must do something physically exhausting until you're totally worn out. Lots of effort. Little to no rewards. High rate of failure. Pavel Tsatsouline suggests that if you want to wear yourself out there is a much easier way to do it, "run up the mountain!" The Belarus born father of the kettlebell also points out that in the Russian language, there is no word or phrase that is directly translatable to "work out."
In this interview and Q&A Pavel discusses how he approaches strength training and physical conditioning as a practice. He refers to his sessions as lessons and treats his clients as students. He pares the very complicated and confused subject of physical training down to the most essential principals that can be used for many applications.
Two techniques from this interview to apply for more efficient practice:
Identify your maximum effort without failure, ie. practicing for one hour. Cut the amount of time in half and focus very specifically on what you need to improve: a phrase, etude, low register intonation, etc. Rest for about 20 minutes or until you feel fresh and then practice another 30 minutes to finish the hour.
Application of mental force and rest. Can you take a nap right before a performance and play your best after about a minute of warming up? Most of us can be over anxious, and spend a ton of mental energy just being nervous. All that needs to be focussed on in performance and practice are the notes. Read: all of your mental energy is poured into each note as you are playing it, not before or after. Before and after is rest.