This thesis is composed of three essays in applied microeconomics. They are related to one another in that they explore if and how individuals make changes to one or more lifestyle behaviours. The first two chapters focus specifically on the response of individuals to a negative health event and how they change numerous lifestyle behaviours. The second chapter zooms in on the impact of personality characteristics on the lifestyle change response. The third chapter explores the determinants associated with, if and how, individuals and households change their diet in the direction of one that is more plant-based. The first chapter studies if individuals respond to a negative health event and, if so, which lifestyle behaviours are driving the change. I find that individuals indeed respond to the realization of a health risk, such as a diagnosis of heart attack or diabetes. However, there is no response when individuals receive only a signal about their health status or risks, such as via a diagnosis of high blood pressure or chest pain. I also find that the main drivers of these results are a decrease in the number of cigarettes smoked and an increased probability to quit drinking alcohol. No effects are found for either diet or exercise. In the second chapter, I investigate how personality characteristics – using the Big 5, a grouping of personality characteristics often used in psychology – interact with the negative health event, to modify the response to the lifestyle changes. I look at the impact of the negative health event for households, who have for each of the five characteristics the high or low value that is associated in the literature with lifestyle changes. The ‘changer-type’ individuals have a greater response to the negative health event than the overall effect found in chapter 1. The effect is found for those individuals who experience an actual health risk realization, but remains insignificant for those who only receive a warning on their health risks. Unlike in chapter 1, where it seems only a few of the lifestyles are driving the results, chapter 2 finds that all the personality characteristics also individually appear to play a role. The third chapter explores household changes towards more plant-based diets to understand better which households determinants are positively or negatively associated with diet change and, possibly more broadly, habit changes. I explore if households make a change towards a more plant-based, and if so, which are the household determinants associated with such a diet change. I also investigate, which determinants are associated with households sustaining the diet change. Finally, I explore if the determinants matter for whether a household sustains the diet for a short or longer period of time. In general, I find the positively associated characteristics are: being vegetarian, being a one-person household, working less than 30 hours per week, changes in education, changes in income, and moving home. The negatively associated characteristics include having children at home, being of white ethnicity or stop working.