During the working day, employees do not only think of their work but also occasionally of their upcoming leisure time. Accordingly, we introduce two constructs, namely thoughts of leisure time (ToLT) and thoughts of a planned leisure activity (ToPLA). We assumed that employees report more ToLT/ToPLA at the beginning and the end of the working day. We further hypothesized that employees with higher pleasant anticipation of a planned leisure activity generate more ToPLA. As leisure thoughts distract attention from work, we expected a negative relationship between ToLT/ToPLA and work engagement within one hour and across the working day. Regarding the subsequent hour, we assumed that when the leisure plan is positive/negative, the relationship between ToPLA and work engagement is positive/negative. We conducted an hourly online-survey across one working day (N = 89 employees, 438 measurement points). Our results revealed the expected time trend for ToLT/ToPLA and a positive relationship between pleasant anticipation and ToPLA. We further found negative relationships between ToPLA and work engagement (within one hour) and between ToLT and work engagement (across the day). Contrary to our expectations, for positive leisure plans, the relationship between ToPLA and work engagement in the subsequent hour was negative.