I spoke to a friend of mine, who is actually a competitive bicyclist in the Tour d'France-ish mode. He said that my description of weekend biking also applies to some degree to competitive, long distance biking: It take a tremendous relaxation combined with intensity, and a skillful mixing of the two. So, while one needs an iron will to overcome the moments of pain and exhaustion, one must be very comfortable and unstressed in the sadle as the road winds around (actually, he said something like that, and I paraphrase).
Thus, I often compare our practice to a bike ride (not the Tour-d'-France version, just an easy bike ride through life). If you try too hard, grip the handlebar too hard, worry which leg must follow which leg ... over you go! But, just, relax, pick up your feet and ride! Our Soto practice is a fine mix of hard effort, no effort, and a skillful union of the two.