He was threatened with a blade at a wooded area near the Co-operative store in Woodhall Street, Chapelhall, Lanarkshire.
The thief pounced at around 4pm and demanded his victim hand over his personal belongings.
He then fled in an unknown direction and the victim, who was uninjured, ran home to report the robbery to police.
The suspect is described as aged around 39, 6ft 1in tall, bald, clean shaven and stocky. He had a foreign accent, possibly Polish or Norwegian, and was wearing a long sleeve jumper with the arms rolled up, with a white collar and navy/light blue horizontal stripes and a motif.
He was wearing dark jeans with a canvas belt hanging down.