Adult hippocampal neurogenesis (AHN) is involved in mood disorders including anxiety and depression. A great deal of work has been placed on identifying strategies to stimulate neurogenesis in mood disorders. Beyond antidepressant drugs, physical activity appeared to be a promising strategy in alleviating both adult neurogenesis and mood. We recently found that individual differences in baseline anxiety-like behaviour negatively correlate with the level of adult neural stem cell (aNSC) proliferation and newborn immature neurons in the dentate gyrus (DG) of the hippocampus. The question of what underlies these individual differences has recently emerged. Very little work to date has looked at the possible relationship between trait anxiety, adult neurogenesis and basal physical activity. Thus, in this study, inbred C57BL/6J male mice were grouped as high anxious and low anxious according to baseline anxiety-like behaviour, measured by time spent in closed arms of an elevated-plus maze and in the dark compartment of a light-dark test. Animals’ spontaneous locomotor activity was recorded twice for 48 hours. Finally, using the endogenous marker KI67, we observed aNSC proliferation in the SGZ of the DG. Here, we demonstrate that individual differences in spontaneous physical activity correlate with trait anxiety and aNSC proliferation. These findings are the first to indicate that basal variability in spontaneous physical activity may partly explain individual differences in trait anxiety and AHN.