Day 1 I learned A LOT. Like running on pebbles hurts. Running on small rocks hurts. Stepping on acorns hurts. Generally pretty much everything I stepped on sent a shock wave through my foot and up my leg. After I started being more aware of the running surface (I don't think I looked up for the next 200 ft), I worked on gait. I shortened my stride leg so I landed over the ball of my foot with each step. The running started to feel better. Which to me seemed like a good time to stop.
Summary of Day 1: Be aware of the running surface. Take steps carefully. Take short strides. And start short. I only ran about 1/4 mile before I put on running shoes and continued to practice the my form. But it was plenty of distance to get the feel for the road under my foot.