Participation in regular physical activity has long been linked to improved cardiovascular health, reduced risk of developing metabolic syndrome and improved mental well-being. More recently, the musculoskeletal benefits derived from weight bearing physical activity (WBPA) have been acknowledged in the latest update of the UK Chief Medical Officers' PA Guidelines. However, few studies have considered a lifecourse approach to relationships between WBPA and musculoskeletal health. Furthermore, the percentage of community dwelling older adults remaining sufficiently active remains low, with few studies considering how this figure may be improved. In this thesis, previously collected data from the Hertfordshire Cohort Study (HCS) were used to analyse the relationship between lifetime participation of WBPA and its relationship with bone mineral density, fat and lean mass and grip strength outcomes in later life. This was followed by a thematic analysis of previously collected qualitative data from a focus group study sited in HCS to understand the barriers and facilitators influencing community dwelling older adults in physical activity participation. These findings informed the construction of a pilot study trialling a participant-led behavioural approach, Healthy Conversation Skills, to improve WBPA, in HCS. The findings from this thesis add to our current understanding of factors affecting older adults' participation in physical activity, in the UK. Positive relationships between WBPA and BMD are reported in women in later life; in qualitative work two key modifiable elements are highlighted: psychological and social engagement as influential factors in affecting the outcome of physical activity level. A pilot study that trialled Healthy Conversation Skills in older adults supports the feasibility of using such an approach in an older adult cohort. A larger trial is now warranted to investigate the efficacy of Healthy Conversation Skills in promoting physical activity in community dwelling older adults.