I've been working as a cashier in a retail store for nearly two years now, and I've loved it. There's been some bad, and a lot of good, but sometimes there are just those customers that make you feel incredible for doing what you do.
We're generally not supposed to 'shop' for our customers, though we of course help them find whatever they need. That said, not but maybe two months ago, and older man came into the store and handed me a small sheet of paper, and walked off. I looked at it, and it listed off a few small items. (I don't recall exactly what they were, but it was only 3 or 4 really small things).
I wasn't exactly sure what he wanted with this, so I walked to him and asked him, though he didn't respond. He's hard of hearing. I asked in a bit of a louder voice, but still didn't get a response. Instead of just continuing to try and get his attention, I walked off and gathered the things on his list. Again, they were small, so it took me all of a minute to gather them all, and I brought them back to him and tapped his shoulder. He looked at the items, and then looked at me, straight into my eyes. And he put his hand on my shoulder and said, word for word, "Thank you, young man. This is exactly what I was looking for. Thank you."
I nodded and said "You're welcome" and went back to my work. It was something really small and simple, but even just thinking back to when he said that makes me just so happy about what I do.