Some other thoughts -
If you notice some habitual thing you do when feeling initial frustration (surf to a website, turn on the TV, whatever) - then try changing your environment slightly to make it harder. If you use Google Chrome, delete or move a site you go to habitually. This can help a lot for not bailing out during that first 15-30 minutes of warmup when working on something a little frustrating and a little beyond current skill level.
Silence is good, but if you have a hard time finding it, try to find music that drowns out the outside world for you. Electronic music helps me - a nice mix of Benny Benassi, David Guetta, or John Digweed and I can ignore background noise. Also, if lyrics distract you and you like electronic, maybe try looking up some "minimal techno" - it's kind of weird, but very cerebral. I work very well to it, it's zone-getting-into music for me.
Silence or kill your phone entirely.
Make very clear to people when you're about to work on something important and don't want your concentration broken, let them know you're going to be an angry cave bear woken up from hibernation if they bother you, and let them know exactly what to bother you on - "Don't disturb me from working unless something is on fire, and maybe not even then" tends to get the point across.
Also, you've kind of got to regular your caffeine/sugar/food a little bit so you don't totally spike and crash. It takes a while to get this down, but there's very few things that are as much of a bummer as having your blood sugar crash, caffeine withdrawl, and hunger kick in all at the same time when you were doing good work. Knowing your own rhythms and eating/drinking/caffeinating intelligently during your work helps a lot.