Inclusion Criteria:  People who are 18 years or above Newly diagnosed with breast cancer Commencing chemotherapy and being prescribed with four cycles of a chemotherapy regimen Mobile phone and WeChat® users (a mobile application of Shenzhen city's Tencent computer system Co. Ltd.) Wi-Fi or 4G network users Able to read and write Chinese  Exclusion Criteria:  People who are pregnant Have been diagnosed with terminal-stage breast cancer (i.e., stage IV) Have a history of chemotherapy Have been prescribed with targeted therapy within three weeks of completing the chemotherapy Have documented mental disorders Have already engaged in other mHealth studies