He's quite fit, fit in a way which is rarely seen nowadays; it's the fitness that comes from exertion and work, not time on Nautilus equipment.  Scars on his hands and forearms attest to a life of manual labor, and his thirty-year-old face alternates between tanned and sunburnt depending on whether or not he remembered to pack sunblock.  That, too, is rare nowadays; in an economy where most people work indoors, Dennis clearly works under the Wenatchee sun.