When people talk about how the second season will be tougher in some ways for the Eagles, they talk mostly about how the schedule appears to be harder and how everyone around the league has had an offseason to study exactly what hath Chip wrought. But another obstacle is health - because the Eagles were almost freakishly healthy last season, and everyone is having a hard time figuring out how much of that was the Eagles' approach to conditioning and how much of it was just luck.