Background <p>Muscle strength is a robust predictor of healthy ageing and vital for independence in later life. Despite their potential reach, there is little evidence that healthcare practitioners are promoting the muscle-strengthening component of the United Kingdom’s (UK) Chief Medical Officers’ physical activity guidelines in practice. This study aimed to objectively measure strength following a very brief intervention (VBI) with the muscle-strengthening guidelines to determine if this could increase muscle strength in adults aged 50–75 years in the resource-constrained settings of primary care.</p> Methods <p>A VBI was delivered to 31 participants. Participants were instructed to follow the recommended guideline <i>‘build strength on at least 2 days a week’</i> and asked to keep a diary of their behaviour throughout the six-month period. Grip and ankle strength were measured at baseline and six-months post-intervention. Quantitative strength and demographic data were analysed, alongside qualitative data from diary records.</p> Results <p>Pre-to-post intervention measures showed a significant improvement in grip strength from the VBI, however changes in ankle strength were non-significant. Age, employment, income, strength training history, and current self-reported strength level significantly predicted intervention effects. Qualitative data provided additional insight into findings and intervention acceptance, highlighting its perceived value alongside requests for further exercise guidance.</p> Conclusion <p>This study is the first to investigate the potential of a 5-minute intervention to increase muscle strength. Results identified a character profile of whom healthcare professionals may best target with this intervention and how to improve this intervention for future implementation in primary care settings.</p>