Firstly, the research student will check the eligibility of cancer children by screening their medical records. The research student will then approach the eligible children who are hospitalized in the wards of the pediatric oncology unit. Written consent will be obtained from their parents after they are told about the details of this study. They will be given an option to participate or refuse their child's involvement in the study. In addition, the children who agree to participate will be also invited to put their names on a special child assent form. Both of them will be assured that their participation is totally voluntary and they are allowed to withdraw from the study at any time. After obtaining the participants' demographics from the parents, the children will be asked to complete a set of questionnaires which consists of the Chinese version of Pediatric Quality of life Inventory, Chinese University of Hong Kong: Physical Activity Rating for Children and Youth and Coping Behavior Checklist. About 20 of them will also be selected at random to have a one-to-one, 20 to 30 minutes, semi-structured interview, and all the interviews will be tape-recorded.