Construction workers are rarely the focus of media campaigns, yet they are among the most exposed to extreme heat. Vest for Rest was created to reach them where no screen or sign could. Instead of placing messages around construction sites, the campaign placed the message on the workers themselves. Using temperature-responsive ink, a safety vest reveals a rest message when the heat reaches 33°C—the legal threshold for mandatory breaks. The vest activates only when needed, turning an invisible risk into a visible signal. Workers don’t need to check devices or wait for instructions. The message appears automatically, allowing everyone on-site to recognize the same moment and respond together. By transforming mandatory workwear into a live communication medium, Vest for Rest shows how media can be tailored to a specific audience through relevance, timing, and context—making safety messages unavoidable, understandable, and humane.