The aim of this study was to examine differentiated effects of internally focused attention in endurance sports. Thirty-two active runners ran 24 min on a treadmill at a fixed speed of moderate intensity. For each 6-min block, participants had to direct their attention on different internal aspects (movement execution, breathing, or feeling of the body) or received no instructions. Oxygen consumption (VO2) was measured continuously to determine running economy. Results revealed that the different internal focus instructions had differentiated effects on VO2: A focus on breathing as well as a focus on the running movement led to higher VO2 than a focus on feeling of the body which showed similar VO2 as the control condition. We conclude that an internal focus of attention is solely detrimental to performance when directed to highly automated processes (e.g., breathing or movement). However, an internal focus on how the body feels during exercise does not disrupt movement efficiency.