Five findings from happiness research that have survived replication, have large effect sizes, and are directly actionable. Not pop psychology — these are the load-bearing ones.

1. Relationships are the #1 predictor of long-run happiness

The Harvard Adult Development Study — 85+ years running — keeps finding relationship quality at age 50 predicts health and happiness at age 80 better than wealth, cholesterol, or any intelligence metric. Invest here first.

2. Hedonic adaptation is real

Lottery winners and people with major disabilities both return to near-baseline happiness within 2-3 years. Chasing happiness through circumstance changes is a losing game; structural habits outlast circumstances.

3. Gratitude practice works — with specificity

Multiple randomised trials show gratitude practice lifts baseline mood, but the active ingredient is specificity. "I'm grateful for my family" is close to placebo; "I'm grateful Priya called from the hospital" isn't.

4. Exercise affects mood strongly and reliably

Effect sizes for moderate exercise on depression symptoms are comparable to medication for mild-to-moderate cases. Not a supplement to real treatment — a primary intervention in its own right.

5. Meaning matters at least as much as mood

Research separating hedonic (feel good) from eudaimonic (meaningful) happiness consistently finds people pursuing meaning without moment-to-moment happiness are often better off long-term than people pursuing happiness without meaning.

The applied version

Invest in relationships. Exercise daily. Practice specific gratitude. Accept that circumstances won't deliver sustained happiness. Pursue meaning alongside comfort. Five findings, applied for a year, measurably change how satisfied you are with your life. Not instant — cumulative.