It's our first instinct to "stop crossing oceans for people who don't even jump puddles" for us. We're human, our flesh is wired that way - if someone doesn't do anything for us, we shouldn't do anything for them. But what if that wasn't always the case? What if we actually changed our attitude towards people/how we treat them? Would you rather be known for doing nothing or recognized for doing good things?
The extra mile is never crowded. How you treat people does not have to be a reflection of the way they treat you.
Cross those oceans. Don't hold grudges. Forgive. Show grace. Yes, that person may not do the same for you, but by you going that extra mile, you may be the only source of kindness that person witnesses. You going the extra mile for them may even lead them to go the extra mile for you.
It can't hurt. In fact, it's good for you. Think about it in the other person's shoes or how good you feel when someone does something for you. Now realize how you have the power to make other people feel like that. For me, making people feel like that makes me feel just the same, and I just bet it would for you, too.
It may not be what you see every day. It may not be considered "cool." But most of the time, the best things to do aren't.