Compromised physical health and raised levels of morbidity and mortality are experienced by young people (16–24 years) with mental illness, and are compounded by psychotropic medication. How this group conceives and experiences physical health is not well understood. We investigated the meanings, beliefs, and endeavours of young people that impact their physical health understandings and behaviours. The present study formed the qualitative phase of a sequential mixed-methods study, and incorporated semistructured interviews with 12 hospitalized young people. Qualitative content analysis was used to analyse data. Participants held a holistic ideal of physical health that they did not meet. Weight change, poor sleep, and limited exercise adversely impacted their lives and self-image. Sedentary behaviour, reduced energy, and limited health literacy compromised effective management of physical health. Young people needed structure and support to assist them in addressing their physical health needs when amotivation overwhelmed their internal resources. Nurses are well placed to help young people increase their competency for health management. Individualized information and methods to promote good physical health are required for this group in jeopardy from physical morbidity and mortality.