I used to live in Hart, just inland a bit (one of two main exits to get to SL, the other being the Shelby exit to the south). I was never one to run around much out there, a bit on quads our friends used to rent out. When I was in high school, though, we used to run a few miles for cross country training. About two miles of that, is like ten on the road, really hard running!
When you're up there, take some time off the dunes and tool around the area. To the south is Little Point Sable lighthouse, to the north is Pentwater, north of that is the hydro electric plant (really sweet, and if you throw disc, there's a sweet golf course up the hillside!), and north of that is Ludington. A great area to visit. A bit on the slow side to live in, though.