I totally agree on the retrospective. Without taking the time to review what you've done, it's harder to stay motivated and measure your progress. Set aside time on the calendar to do this because it's also a very good time to review your goals. Remember, tasks should move you closer to your goals!
What's your strategy for getting in the "Zone"?
I like to throw some pomodoros in each day. I feel that at first it is a tad awkward. However, after you get used to it, you feel the need to really finish a unit of work in the allotted time. I feel that the pressure to get into the zone quick and practicing it helps. For those unfamiliar: pomodoro is 25 minutes uninterrupted work, 5 minutes break. Rinse, repeat.
I like to add in some noise canceling headphones into the mix to help with the interruptions while trying to execute a pomodoro. A cold hard stare helps too :)
I like using pomodoros periodically. I find that I don't always need them, but if a day or two goes by where I'm feeling unfocused, using them for a couple of days gets me back on track.