While waiting for a bus or sitting on a train, your first inclination (if you’re an extrovert) is probably to turn to your left or right and strike up a conversation. Do not do this in Sweden. It’s not that Swedes are inherently rude; it’s just that they prefer maintaining their silence. That’s why there’s very little talking going on in Swedish public transport.
Wherever you are—in line at a coffee shop, at a bus stop, or even crossing paths with your upstairs neighbor—there’s no time to talk. Heck, there’s probably no time to smile, either. Just go about your business and you won’t be labeled as a social outcast.