I should have known that I would not escape from my first long run without a pain or two, but I have to admit I am a tad worried. About 3 hours after I finished I started feeling a pain on the middle-bottom-left of my left foot. Now I am limping around wincing on every step. Apparently this is where the Peroneus tendon attaches to the foot. Of course I googled the heck out of this and have read lots of posts from runners all over the world about this specific issue. This is very common for runners who run a lot on treadmills who then start road running. Or runners who start running trails after only runnnig on roads. This is cause when the stability muscles of the leg and foot become strained. The recommendation is to let it heal and then add some stability exercises to your daily regime.