This chapter illustrates the empirical and processual study of affect. By drawing on a posthumanist practice theory, we conceive a research practice as an agencement of heterogeneous elements that achieve agency by entanglement, focusing on how affect realizes ‘agencing’. We experiment with ‘slow seeing’ as a research practice in our engagement with the digital materiality of a video produced for promoting welfare technologies in Sweden. We follow our ‘becoming-with’ the main character of the video and her digital embodiments as ‘self-in-control’, a ‘vulnerable’ body, a ‘technologically mediated body’, and the body of a ‘happy consumer’. From affect theory, we borrow the concept of ‘happy object’ as a method to engage the flow of performative ‘becoming-with’ ideas, values, and objects. Our contribution in theorizing the process of atmospheric attunement is noticing how the labour of attuning proceeds in iterations of sensing, becoming, and becoming-with.