There was an article in the August 2, 2010 edition of the Bearden West Side Shopper-News (online edition not available) about Chuck Anderton, who is an electrical engineer at KUB (Knoxville Utilities Board) in downtown Knoxville. He has "walked, run, or biked" to work for the past 42 years, and his last sick day was in 1981. His commute ranged from 1 to 7 miles each way, depending on where he lived. He bikes from April to September, where there is light both ways. The other days he tends to walk, even though it does take a while. Needless to say, he's a very healthy individual.
One of the big draws of urban living is being close to most of the things going on, and of having an easy, short commute. Interestingly, truly urban areas have bikes and cars move at roughly equal speeds which means that facilities such as bike lanes are unneeded in such areas. For instance, Gay St in downtown Knoxville is considered one of the finest places to ride.