Developing effective Virtual Reality (VR) applications requires integrating user-centered methodologies into the software engineering lifecycle. Traditional VR development often focuses on predefined environments, limiting user input in the design process. This study presents a user-centered participatory approach to developing VR relaxation experiences, where users engage in immersive 3D drawing to help define design requirements rather than having them interact with predefined environments, as in previous studies. Our findings show the importance of incorporating multisensory stimuli, balancing embodied and calm interactions, and integrating mood-based personalization for relaxing VR experiences. These results suggest effective strategies for enhancing user-centered design in Software Engineering and improving VR relaxation experiences.