There is a paucity of research that examine the psychological state of mobile phone users while creating passwords, and how it affects the choice of strong and weak passwords. In this paper, we examine how a user’s mental state and personality affects choice of user’s password. Therefore, we use two groups: experimental and control, each of 16 subjects, who were asked to generate a password. At the beginning, all participants used the BMIS and the BFI tools to self-report their mental state of mind and personality, respectively. Then, we exert mental fatigue on participants in the experimental group while those of other group were not. At the end of the experiment, we measure and compare password strength across groups. Our findings reveal that the effect of the different mental states on password over our limited sample size is not so different, although more mentally fatigued users tend to create weaker passwords than others do. Further, we demonstrate that a relationship exists, nonetheless, as indicated by our regression model. We also investigated personality and its implication on password strength, the study reveals that participants who report as agreeable are more likely to create better passwords than conscientious participants or extraverts.