Inclusion Criteria:  Stable patients, older than 18 years of age, with a diagnosis of interstitial lung disease Understands and is able to work with a smart phone application (judged by the investigator) On stable pharmacotherapy Diffusing capacity of the lungs for carbon monoxide (DLCO) ≥30%predicted  Exclusion Criteria:  On the waiting list for a lung transplantation Life expectancy below 3 months Respiratory tract infection or an exacerbation or change in maintenance medication within 4 weeks before study enrolment Extra pulmonary impairments, unrelated to the underlying lung disease, interfering with physical activity