Stepping off the beaten path challenges that fear. Grass, a deer trail, sandy dune, soft meadow, or a spongy marsh asks so much more of the body. All those little muscles, tendons and ligaments that become so used to the straightforward pounding of the sidewalk, are stretched and strengthened in ways I didn't think possible. My running partner on that first trail run assured me that in time, those muscles will strengthen and lend me greater confidence in my stride.
It has been so worth it to get off the beaten path, even when in the city and I'm only a couple of feet to the side of my beloved pavement. In the country, however, that is where the true pleasure lies. To see a flock of wild turkeys, or a mob of deer when rounding a bend in the grass makes the discomfort insignificant. For that, I now save my off days for the trail.