It would not be hard to remove mist in Photoshop (Autolevels/Autocontrast). If your idea was to leave the mist visible, you should come closer to the boy - he would become sharp and the background would be misty.
I love this. i can really relate too. my little nephew is always on the move. you captured a great moment in this. i really like his pose and position in the frame and how his eyes are hidden. i'm just not sure about the contrast..i think i would like this better with more contrast. the way it is makes it actually looks like fog... or is it fog? anyway, great image overall. :)