Longer product life – a threat to business, or a way towards long-term profitability and reduced environmental load? The vision of a circular economy proposes that companies can become more profitable and sustainable by adopting so-called circular practices. This aspiration has inspired many manufacturing companies to start their transition journey from a traditional linear to a more circular business by exploring how to close material flows, improve eco-efficiency, and utilise renewable energy. The opportunity to extend product lifetimes, however, remains underexplored although it has potential to contribute significant environmental benefits. Some may see longer product life as a threat to business since it may negatively affect sales of new products and profitability for companies dependent on linear business logic, especially for those that produce and sell products in large volumes. The idea of extended product lifetimes challenges traditional logics of designing for a reasonable lifetime or planned obsolescence. In this guide, we argue that longer product life can be a pathway towards long-term profitability and value capture within the limits of the planet. Emerging global trends also favor longer-lasting products. Upcoming legislation will put more pressure on manufacturers to enable repair, offer spare parts, and provide information about expected product life. More frequent material and component shortages as well as price volatility will make excessive material use less profitable. Rising global consumer awareness will also pressure companies to deliver longer-lasting products. In this guide, we present practical ways to design products for extended lifetimes that are suitable for circular business models, which have the potential to preserve and capture embedded values over time. We believe that companies that design, manufacture, or offer durable goods are the ones that can benefit the most from finding ways to extend product lifetimes. Companies that develop and offer fast-moving consumer goods or consumables can nevertheless also benefit from considering opportunities to increase longevity. This guide is for change agents who have already started or who want to take on the challenge of designing longer-lasting products and implementing circular business models. This includes designers and engineers, business and design managers, and those in top management that create enabling conditions so that products can be designed for longer lifetimes.