The Vogon Guard is described as "huge" and "young".
Arthur Dent and Ford Prefect encountered this young member of the Vogon Guard Corps while on board the constructor fleet. He enjoyed shouting "resistance is useless!" at them, which was the first phrase he'd learnt when he joined the Vogon Guard Corps.
When Ford enquired as to whether the guard enjoyed his job, he told him that the hours were good, but that most of the actual minutes were "pretty lousy". According to his aunt, being a spaceship guard was a "good career for a young Vogon", as it included a uniform, a low-slung stun ray holster, and mindless tedium. Although the guard didn't seem to know why exactly he was doing his job, he couldn't think of any alternative, and thought he'd better stick to what he knew, hoping to eventually be promoted to Senior Shouting Officer.
He seemed to have no issue with half-throttling his prisoners, causing Arthur to become "too asphyxiated to speak", at one point.
- All quotes from pages 56-59 of The Hitchhiker's Guide to the Galaxy novel, 1979