From Bicycling Almost every morning before work, I take my dog Rosie for an off-leash adventure on the trails near our house. I run or ride a mountain bike; she sprints at warp speed, skinny legs churning, tongue lolling out of the biggest dog-grin. It’s the best part of both of our days. While I stay on the trail, she runs into the woods, chasing and exploring and sniffing like dogs are meant to do. It seems like she’d run forever.