A free, self-paced textbook in 7 chapters. Read a chapter, then drill it with the 234 companion flashcards using spaced repetition.
A habit is an automatic behavior triggered by cues and repeated until ingrained. Charles Duhigg describes the mechanism as a habit loop: cue leads to craving, which triggers a resp...
Behavior is heavily shaped by context, so environment design uses physical and digital surroundings to make good habits obvious and easy while making unhelpful ones invisible or ef...
Sleep is foundational rather than optional. Most adults need 7–9 hours per night, and the architecture of sleep matters: REM sleep supports memory consolidation and emotional proce...
Physical activity is one of the strongest single predictors of healthspan. The WHO recommends at least 150 minutes of moderate or 75 minutes of vigorous activity per week, plus str...
Nutrition is fuel, signaling, and substrate for the body's systems. Protein needs scale with activity and age: roughly \(0.8\ \text{g/kg}\) minimum for adults, and \(1.2\)–\(2.0\ \...
Mindfulness is non-judgmental awareness of the present moment, while meditation is the practice that trains it. Common techniques include focused attention (on a single object such...
Relationships are the strongest predictor of well-being across decades. The Harvard Study of Adult Development, the longest-running study on adult life, found that relationships mo...