I came across this paper a decade plus ago and it stuck with me. Specifically, there were a few things:

1. We derive pleasure from anticipation, so ensure there are a number of things to look forward to.

2. Likewise we derive pleasure from looking backwards -- so the above is a two-for-one.

3. When making decisions in realtime, we tend to slip into "reptile-thinking" and that in turn leads to unhappy-decisions. They cite a snickers bar versus an apple. So try to make more decisions upfront, aligning them with your goals. e.g. bulk cook versus figure out lunch daily.

4. Day-to-day life has a huge impact on our happiness but we often architect it in ways that make us unhappy. e.g. moving into a big house in the burbs and therefore having a long commute. Think about our goals and design daily life so they flow more readily.

Edit to add my own twist on the paper and a challenge:

If you're so smart, why aren't you happy?