Recognition
People love being recognized for doing something. It's human nature. And yes, it sounds obvious but it bears being repeated.
I learned this at a previous company I worked at. I worked in sales and we had a slack channel with the entire sales organization in it. Every time someone got a sale, their sales manager would give them a big shoutout in that channel. It doesn't seem very significant but I know for a fact the sales reps liked it because I liked it.
People want public recognition for their hard work. If you're in a position of power, give them that recognition.