The present study tested a short intervention using goal-pursuit strategies to increase physical capacity in pain patients. Sixty chronic back pain patients were randomly assigned to intervention or control conditions. Both groups followed a 3-week conventional back pain program at an outpatient back pain center. Instead of routine treatment, the intervention group received a one-hour intervention consisting of a combination of (a) a goal-setting strategy (i.e., mental contrasting, MC) aimed at commitment to improved physical capacity, (b) a short cognitive behavioral therapy-oriented problem-solving approach (CBT) to help patients overcome the obstacles associated with improving physical capacity, and (c) a goal-pursuit strategy, i.e., implementation intentions (II) aimed at performing physical exercise regularly. At two follow-ups (3 weeks after discharge and 3 months after returning home) the MCII-CBT group had increased its physical capacity significantly more than the control group as measured by both behavioral measures (ergometer, lifting) and subjective ratings. Findings are discussed with relation to the use of the intervention as a specific treatment to increase chronic pain patients' motivation to be physically active.