The third wave of HCI research has interest in understanding how technologies can mediate personal experiences and improve life quality. In particular, immersive environments combined with the practices of mindfulness meditation have a strong potential to increase the user's attention to the self. Often, people feel disconnected from their bodies and experiences, and guided attention to self can alleviate this disconnect as in focused-attention meditation. In focused-attention meditation, breathing often constitutes the primary object on which to focus attention. In this context, sustained breath awareness plays a crucial role in the emergence of the meditation experience. Hence, we designed a virtual environment for head-mounted display that supports sustained attention on breathing by employing users' breathing in interaction. The virtual environment depicts an abstract ocean in which one is immersed, accompanied with a generative soundtrack. Both sounds and visuals are directly mapped to the user breathing patterns, thus bringing the awareness researched. We conducted micro-phenomenology interviews to unfold the process in which breath awareness can be induced and sustained in this environment. The findings revealed the mechanisms by which audio and visual cues in VR can elicit and foster breath-awareness, and unfolded the nuances of this process through subjective experiences of the study participants. Finally, the results emphasize the important role that a sense of agency and control have in shaping the overall quality of the experience. This can in turn inform the design specifications of future mindfulness-based designs focused on breath awareness.