Your gearing sounds way high to me. I ride fixed on some longish (90+) rides at a bit under 70 gear inches.

Other than that, I would be sure you have a tool to remove the back wheel in case you get a flat. (Assuming you aren't using a quick release.) I also have a freewheel on the flip side of my fixie, and sometimes I'll switch over to it if I'm feeling beat on the ride home.