The present study used a single-task paradigm in which participants received guidance to focus more attention (waiting for someone) on the temporal intervals in the “waiting” condition and to stay relaxed in the control condition. The reported time was longer in the waiting condition than in the control condition. Functional near-infrared spectroscopy was used to measure simultaneously the activation levels of the dorsolateral prefrontal cortex (DLPFC) for each condition. Greater oxyhemoglobin (oxy-Hb) activation in the waiting condition was observed compared with the control condition, whilst deoxyhemoglobin data showed no difference between the two conditions. The gradual changes in oxy-Hb in the DLPFC in increments of 100 ms yielded further insights into the role of this region in the “watched pot never boils” phenomenon.