Good
nirvana - (in Buddhism) a transcendent state in which there is neither suffering, desire, nor sense of self, and the subject is released from the effects of karma and the cycle of death and rebirth; it represents the final goal of Buddhism

As the Buddha meditated under the banyan tree, a serene glow seemed to appear around him when he finally achieved nirvana.
simmer - To heat a liquid, usually a stew or soup, just below the boiling point, allowing it to cook slowly; or to stay in a slow, controlled state of progress or tension, often before a larger event or change occurs.

He was simmering with anger, but he kept it inside and didn't say out loud what he was thinking and feeling.