You’ve probably encountered people who seem to have a perpetually sunny disposition—those Pollyannas who exude happiness. But what is their secret? According to research, there are 3 key ingredients for true happiness: Internal factors include a sense of contentment and fulfillment, as well as personal growth. External factors include strong relationships and a positive outlook on life. Happy people also have a “glass half-full” mentality, and they express their appreciation for the things in their lives.