Described embodiments include a portable electronic device. The device includes a shell and a heat-generating component. The device includes a first and a second exterior heat-rejection element. Each heat-rejection element is configured to reject heat received from the heat-generating component into an environment. The device includes a controllable thermal coupler configured to regulate heat transfer to the first and second heat-rejection elements. The device includes a first proximity sensor configured to determine if a user touch to the shell is within a first zone of possible heat discomfort. The device includes a thermal manager configured to regulate heat transfer by the controllable thermal coupler to the first and second heat-rejection elements. The regulated heat transfer includes adjusting heat rejection away from the first heat-rejection element and toward the second heat-rejection element if the user touch is within the first zone.