Through a series of systematic steps, including focus groups and interviews with older adults and health care professionals, the investigators have recently developed a brief, positive affect intervention - designed to improve short-term mood in older adults and be deliverable within primary care. It is hoped this could act as a psycho-behavioural adjuvant to enhance poor responses to influenza vaccination in older adults. Before performing a definitive trial of the intervention's effectiveness, a feasibility trial is needed for number of reasons: