Active Living Research, Department of Family and Preventive Medicine, University of California San Diego.
Correspondence: James F. Sallis, PhD, Active Living Research, Department of Family and Preventive Medicine, University of California San Diego, 3900 Fifth Ave, Ste 310, San Diego, CA 92103 ([email protected]).
This work was supported by Active Living Research, a national program of The Robert Wood Johnson Foundation.
Disclosure: The author declares no conflicts of interest.
doi: 10.1097/PHH.0b013e318262cbf6