The intervention consists of an individual counseling session, telephone counseling (7 calls), given by a psychologist, and a pedometer. The intervention is based on cognitive behavioral therapy, the Diabetes Prevention Program, the first Step Program and Motivational Interviewing. The taxonomy of behavior change techniques is also taken into account. The duration of the intervention is six months. The individual session takes place one week after the baseline measurements, together with the participants' follow-up appointment with their endocrinologist. The individual session takes place at the endocrinology department and is expected to last approximately 30 minutes. In addition to the session, the participants of the intervention group receive a pedometer and a pedometer diary for six months. Participants of the intervention group also receive telephone counseling from the psychologist during 24 weeks. They receive a call every two weeks for four weeks and then every four weeks for the next 20 weeks, good for a total of seven counseling calls. The calls are expected to last approximately 20 minutes. The Control Group has no intervention at all and receive their usual care.