Nintendo clearly wants us to be carrying the upcoming 3DS around with us as much as possible; with the StreetPass feature alone, gamers are being encouraged to take their 3DS systems to the street and see what treats await them simply by passing fellow gamers out in the real world. The incentive doesn't stop there, though.
In connection with the 3DS's built-in Activity Log ― which tracks how many hours you have spent on your precious games, as well as acting as a pedometer, providing graphs and charts which depict your walking habits ― the system will reward gamers with coins based on how far they have traveled on their feet. These coins are then used to access additional content in games.
True, pedometers can be "tricked" into thinking physical walking is being performed, but even cheaters will be carrying their 3DS systems when out and about as there's not a lot of reasons why they shouldn't. Along with the fact that collecting coins isn't the sole purpose of the StreetPass mode, we think (honest or otherwise) Nintendo handheld gamers will be carrying their 3DS systems with them with no qualms whatsoever.