<p>This study examines the role of anticipated job demands in shaping the type of ruminative thoughts employees engage in during work breaks and how these thoughts influence post-break energy levels. Drawing on the challenge-hindrance framework and a Control Theory approach to rumination, this article hypothesizes that anticipating challenge demands fosters constructive rumination (problem-solving pondering), while anticipating hindrance demands leads to unconstructive rumination (worry). The impact of these ruminative processes on post-break energy levels is also explored. A time-separated cross-sectional survey was conducted with 246 full-time employees from the UK, who reported their anticipated job demands and ruminative thoughts before and after breaks, respectively. Structural equation modeling revealed that anticipation of challenge demands positively predicted problem-solving pondering, while anticipation of hindrance demands was linked to increased worry. Notably, worry during breaks was associated with reduced energy post-break, while problem-solving pondering showed no significant effect on energy after energy levels before the break was controlled for. These findings highlight the nuanced effects of different types of rumination during breaks and suggest that while constructive rumination may not harm energy levels, unconstructive rumination can be detrimental. The study contributes to the work-break literature by linking job demand anticipation with ruminative thinking and subsequent energy, offering insights for optimizing break design to enhance employee well-being.</p>