The stranger beside you does not need to become useful before being treated pleasantly.

It is easy to treat strangers as potential resources, warmer with the ones who might turn into a contact, a customer, or a friend, and neutral with everyone else. That calculation is usually invisible to the person doing it and perfectly obvious to the person receiving it. Ordinary courtesy is not an investment with a poor return; it is how the day is made bearable for both of you.

Be pleasant to two people this week who can do nothing for you. Expect nothing back and notice how it changes the hour anyway.