I've always thought of things like meaning, mission, and purpose as higher-level needs, but the more I learn, the clearer it becomes that meaningful work is a basic human need that crosses professions and income levels.SC: Write about the importance of positive social interactions. What does this mean for introverts, who often prefer to spend social time in small doses, with close friends and punctuated by solitude? TR: There is nothing more appealing to this introvert than a combination of solitude and some time with my closest friends. Perhaps this is why research on the relationships between positive and negative interactions has always struck me. The quality of social interactions matters much more than the frequency of those interactions. From what I've studied, about 80% of our interactions with other people need to be more positive than negative. This is simply because negative interactions carry a much heavier load and outweigh positive ones