RecruitingBehavioural interventionPain Disengagement Training (Open Pilot)The investigators aim to conduct an open pilot trial to determine the initial feasibility of a self-directed writing-based intervention in individuals with chronic musculoskeletal pain and elevated pain catastrophizing. The investigators will assess the feasibility of recruitment, acceptability of the treatment, credibility and participant satisfaction, treatment adherence, and feasibility of assessments following pre-specified benchmarks.