Inclusion criteria  Aged 18 years and above; Diagnosis of non-small cell lung cancer or small cell lung cancer Fatigue symptom score ≥4 out of 10 Self-reported engagement of <150 minutes of moderate-intensity PA each week Ambulatory and capable of all self-care activities Either undergoing or finished oncology therapy and/or support care Mentally, cognitively and physically fit to join the trial Able to speak and read Chinese; Willing to complete the patient-reported outcome questionnaire Completion of the Physical Activity Readiness Questionnaire Possession of a smartphone with instant messaging functions such as WhatsApp or WeChat.  Exclusion criteria  Those preparing for lung operation Skeletal fragility Serious active infection Inability to walk Severe respiratory insufficiency Uncontrolled pain Diagnosed psychiatric illness such as major depressive disorder