This one has been a little hard for me lately, which is no excuse. The skill exists regardless of my feelings. It is a thought exercise, not an emotional one.
Empathy is the ability to put yourself in another's place, even if you've never directly experienced what they're experiencing. Most people are completely incapable of doing this. This explains some of the incredibly stupid and hurtful things people say with good intentions at funerals. If you've experienced loss, you know it's better to keep your jaw clenched shut until you get home.
I've heard that people who read fiction have more empathy because they've experienced other lives through the written characters. Whatever. Good excuse to read fiction, as if you need one.
Your universe revolves around you. This is completely normal. However, at some point, you should realize that this is how every person experiences life. We are all little Suns thinking the entire universe rotates around us, when, in fact, we're lucky if we're one of those bits of shattered planet that circles Saturn or Jupiter.
When you understand you are not the Center of the Universe, you can start imagining what it would be like to be your customer. You work at Walmart (or don't. I mean, have you ever been asked where to find something in a store? It's because I have a "pleasant resting face," I know it is). Anyway, your customer needs X. You had a million things to do before the customer ever walked up. Congratulations! You now have a million and one. And you're going to treat Million and One like Number One because that's what you would want if your positions were reversed. If you needed X, would you want an employee who brushes you off and waves a vague direction with a mumbled reply, or one that leads you to the spot and hunts down the item? I will settle for clear directions and a specific pointed direction, but I'm more independent than most.
An old lady with a quavering voice calls in, and your heart sinks because she's going to take forever to help. Do you think she doesn't know that? Do you think she's not embarrassed by the quaver in her voice, or her slowness? She remembers when she was a fast, young whippersnapper like you, and she could leave you in her dust back then. She's someone's grandmother, for goodness' sake, not your personal hobgoblin! Show respect, treat her with the kindness and patience you would want extended to you (or your grandmother) in the same circumstances, and let God sort out the rest.
Empathy allows you to put your issues on hold, and help someone else in a calm, courteous way because that's how you would want to be helped. Empathy is essential in good communication, and it's quite useful in customer service.
Push button. Receive bacon.