We produce vast amounts of data in our daily lives. Email, text, search, check-in, photos, payments – all these activities create a trail of digital exhaust. This personal data has been triumphantly declared a “new asset class” by the WEF, compared to oil as the world's newest economic resource, and sparked a big data race to gather it. This paper argues that this gold rush can obscure the real value of personal data by forgetting a fundamental rule of innovation: start with the person. The paper draws on global ethnographic research with data-driven individuals, experts, and start-ups to address five common misconceptions about personal data. It concludes with a set of simple principles and business case examples to bring a human-centred, small data perspective to life.