Cybersickness is common during head-mounted display (HMD) based virtual reality. This study examined whether it is possible to: (1) identify people who are more susceptible to this cybersickness; and (2) find general ways to reduce its occurrence and severity. Our participants were exposed to HMD-based virtual reality four times over two different days (using “Freedom Locomotion VR”). During these 10-min trials, participants were either free-standing or posturally restrained as they actively controlled or passively viewed their locomotion through the virtual environment. Cybersickness was found to increase steadily over time during each exposure. While this cybersickness was markedly reduced on day 2 (compared to day 1), it was not significantly altered by either the use of postural restraints or active locomotion control. However, the sick and well participants in our study were found to differ in terms of their spontaneous postural activity (before they entered virtual reality). We found that the participants who experienced stronger vection also tended to report more severe cybersickness in this study. These findings suggest that we should be able to identify people who are more susceptible to cybersickness and help them become more resistant to it (via repeated exposures to HMD-based virtual reality).