My friends and I are considering running the Rock Marathon, on Sunday December 9th in Dallas. That leaves us 5 weeks to train for it. Currently we just finished cross country season (5K's), so were in pretty good shape, but definitely need to increase our mileage. We've run about 5 miles a day for cross country (although we did taper a little at the end of the season). Is this going to be possible? We're not looking to go out and win; just to finish. Any training tips?