Study to Evaluate the Impact of the "PROactive Telecoaching Program" on Physical Activity in Patients With COPD.

Inclusion Criteria: * Written informed consent * Male and female patients ≥ 40 years of age * Diagnosis of COPD (GOLD criterion: post bronchodilator FEV1/FVC\< 70%) * Current or ex-smokers with a smoking history equivalent to at least 10 pack years (1 pack year = 20 cigarettes smoked per day for 1 year) * Patients should have at least 4 days of physical activity data recorded via activity monitor during 7 days prior to visit 101. Exclusion Criteria: Patients fulfilling any of the following criteria are not eligible for inclusion in this study. * Orthopedic, neurological or other complaints that significantly impair normal biomechanical movement patterns, as judged by the investigator. Specifically if the patients' condition/ co-morbidities are such that physical activity cannot be increased. * Respiratory diseases other than COPD (e.g. asthma) * Cognitive reading impairment and/or difficulties to manage electronic devices precluding interaction with the health base and PDA, as judged by the investigator * Participating in or scheduled to start a rehabilitation program during the study. If the patient wishes to participate in pulmonary rehabilitation for any reason the patient can be enrolled in the study only at the end of rehabilitation. * Women of child-bearing potential who have the intention to become pregnant during the course of the study and pregnant or nursing (lactating) women, where pregnancy is defined as the state of a female after conception and until the termination of gestation, confirmed by a positive β-hCG laboratory test.