What do scientists do in their spare time? Do they play hard as well as working hard, or do they find it difficult to leave their work behind? Do they actually want to make a distinction between work and pleasure, perhaps explaining why so many of them continue research in retirement? Are their hobbies closely linked to what they do at work, or an escape from it? Our interviewees suggest that there are many different answers to these questions and that the balance between work and personal life changes over time. Accounts of hobbies and outside interests are often more closely associated with student years and early career, later being replaced by family responsibilities before reappearing later in life.