Objective: To investigate the influence of grit on physical activity, sleep and diet in undergraduate students during the COVID-19 pandemic. Participants: 125 undergraduate students participated in the study. Participants completed an online survey while enrolled in an online class during June, 2020. Methods: The online questionairre featured the following validated survey instruments: International Physical Activity Questionnaire Short Form, Pittsburgh Sleep Quality Index, the Rapid Eating Assessment for Participants Short Form and the grit short form. Effects of grit on lifestyle behaviors were explored using several statistical approaches. Results: We found that individuals with more grit reported better eating and sleeping behaviors compared to those with less grit. However, we did not find an influence of grit on physical activity or sitting time. Conclusion: Our findings support that personality traits encompassed in grit contribute to college students reporting healthier dietary habits and better sleep quality during a global pandemic.