There's this little saying I've heard in yoga many times (especially Bikram classes). It goes, "You can't do the posture with your face."
As in: go ahead and relax your facial muscles, relax your mind, relax everything you can, all those muscles that you don't need to do the posture!
Because furrowing your brow and straining your forehead aren't going to help much. Plus, it's so much more calming to do a challenging pose if you can let go of tension in your face. It's a great little instant relaxation technique.
I was reminded of this during my bike ride to work this morning, as the wind pushed hard against me, taking my breath away and keeping me in the 1-5 mile per hour speed range. I realized, hey, I can't ride this bike with my face! and figured I might as well stop trying :) It worked -- I enjoyed the rest of the windy way there much more after that.