It's easy enough to tell people about your religion but not everyone is so good at practicing what they preach. Ashoka, though, did seem to genuinely believe what he was telling people, or at least was smart enough to be a Buddhist king in action as well as in word. He worked hard to spread Buddhism across the realm, but he didn't force it on anyone. In fact, according to National Geographic, he had a pretty strict policy of religious tolerance, which you don't usually expect to see in the ancient world.
He was also smart enough to know that if people are going to listen to you, you have to speak their language — literally. One of the things Ashoka is most remembered for is the edicts he had carved into stone pillars and other monuments across his domain, always in the local dialect.
Ashoka could have just been preachy without really doing anything to help anyone, but he also seemed to genuinely care about his subjects. He ruled with kindness, and would often travel his domain to make sure that his subjects were okay, or as okay as anyone can be if they were mostly poor and living in the third century BC. And he did work towards improving everyone's living conditions, too — in addition to all the new Buddhist temples he put up, he also built and maintained roads and helped bring irrigation to dry places.
