The Buddha famously said, "I teach dukkha and the end of dukkha." Yet what does this core statement of the teachings mean? In this talk, we explore at least four meanings of dukkha in the discourses; not recognizing these different meanings can lead to considerable confusion. Only one of these four meanings of dukkha, dukkha as reactivity, helps us to understand directly "the end of dukkha." We look particularly at the teachings of the Two Arrows and of Dependent Origination to support the understanding of dukkha as reactivity, clarifying some of the complexities of the teaching (including that very commonly our reactivity is mixed with some insight, pointing to how what is important is to "transform" reactivity rather than simply suppress it or get rid of it). Lastly, we suggest a number of different ways to practice with reactivity. The talk is followed by a period of discussion.