Last year, Payam Rajabi got a new job and had to leave Toronto and his girlfriend Clare and move to San Francisco. All that left him feeling a little down — until he came up with his upsy, downsy Valentine idea.

He jumped on his bike, opened his iPhone to a map of San Francisco, and tracking himself with a GPS, he rode 27 miles around the city, taking two and a half hours, burning 1,135 calories and carefully etching a heart shape onto a city map ... like this ...