Create a realistic 3D rendering of a classic smartwatch designed for fitness tracking, prominently displayed on a sleek office desk. The smartwatch features a customizable watch face showcasing vibrant colors and fitness metrics, such as heart rate and step count. The metallic shades of the watch gleam under soft, diffused lighting, enhancing its modern appeal. In the background, include elements of an office setting, such as a laptop, a notepad, and a coffee cup, subtly blurred to maintain focus on the smartwatch. The overall atmosphere should be bright and vibrant, conveying a sense of professionalism and advanced technology. Ensure the details of the watch, including its buttons and screen interface, are clearly visible, emphasizing its functionality and style.