Cycling Cuts Emissions...but What Else?

This article from the Guardian about a study of carbon emissions caught my eye.  Apparently if we all cycled as much as the Danish we would cut our transportation based emissions by as much as 25%.  Important to note that it is not overall emissions, just from transportation.  But still, it is nothing to sneeze at.  The article later notes that the estimates might be underplaying the amount cut:

This figure is likely to be a significant underestimate as it deliberately excludes the environmental impact of building road infrastructure and parking, or maintaining and disposing of cars.

These kinds of studies are interesting in and of themselves but I prefer to think about the overall impact of cycling if we up the amount of miles on foot and by cycling over using motorized transport.  It seems like the larger health and quality of life issues are far more important in the long term.  I mean that if, as the study says, the average Dane cycles 600 miles a year, what are the far reaching effects that would have on the mental and physical health of Americans if they adopted cycling for an equivalent amount of transportation miles?

More:

It also points to the example of cities such as Seville in Spain, where the construction of segregated bike lanes and other policies saw cycling increase tenfold in just three years.
"It is possible," said Ferguson. "It just takes a bit of political will and a good dose of cultural change."