Many mothers initiate breastfeeding, but some of these experience difficulties. This study has two aims in order to contribute to the development of optimal care for these mothers: firstly to explain and understand the existential meanings of one mother's severe initial breastfeeding difficulties and how these meanings affected her continued breastfeeding and secondly, to reflect on a method for applying lifeworld hermeneutics to research on complex breastfeeding phenomena. This is an approach that acknowledges and focuses on the concrete and lived existence and what it means for humans. Within this approach, humans are understood as whole human beings interacting in the world. The study was conducted using lifeworld interviews with Anna, focusing on meanings of her difficult lived experience of initial breastfeeding. The existential interpretation suggests that such an experience can evoke existential vulnerability, a vulnerability that becomes evident in shameful feelings, such as dislike of breastfeeding, aversion to the milk-producing body and anger towards the child. Anna continued breastfeeding as a way to rid herself of the shame, hoping to be confirmed as a good mother. Such an experience may have negative consequences for the mother-child relationship and it can create fear for future breastfeeding. This study concludes that carers should be aware of individual existential dimensions for breastfeeding mothers.