Process evaluations of newly developed interventions are necessary to identify effective and less effective intervention components. First aim of this study was to identify key components of a psychosocial goal management intervention from the perspective of participants, and second aim was to evaluate the intervention’s fidelity. A mixed-methods approach was applied to 24 interviews with participants post-intervention and 16 audio recordings of random training sessions. Participants experienced three key components: (1) the content, in which specific exercises helped to raise awareness and (intention to) change goal management behaviour, (2) person-focused approach, specifically, the nurse as trainer and personal fit of the approach, and (3) social mechanisms, including facilitating group processes and interpersonal processes. Adherence to the protocol by the trainers was high, while differences were found in the degree to which they were able to apply the intended collaborative approach and psychological communication skills. The applied design provided valuable insights into the processes that took place. Both the effects experienced by participants in relationship to the content, approach and social mechanisms as well as the strengths and weaknesses found with regard to fidelity provide insights that can inform the development and implementation of person-focused interventions.