I found it was easier to take more short strides rather than fewer longer ones. Having a stride that's too long for your body will exert too much force on the rear of your heel since all the impact of each step will occur there. That will cause blistering and possible stress fractures. Too many blisters/swelling and you'll end up cutting the front and back of your boots off and end up walking around in a nice new pair of leather Tevas.
Like others have said, I definately found swinging my arms back and forth worked well. Let your arms extend all the way so your muscles don't work extra to hold up your weapon (obviously for non-combat environments only).
I always tried to trot a little extra on the down hills - gravity is your friend in this case.
Maybe rucking the same path over and over subconsciously subdues you a bit. Try varying your terrain.
Don't zone out, but stay in a slightly detatched mental state. It'll relax you and you'll fall into a 'groove'.
Picture yourself after you graduate the Q and you find yourself in Iraq, separated from your team, with 100 locals chasing you so they can cut your head off and put the video of it on YouTube.
-Good luck LT.