This chapter shows that how habits are formed, why eating habits are so hard to change and the reasons for failed dieting, both in terms emotional triggers, of what’s in our heads and factors in the environment such as physical triggers and social pressure. Habits are formed through four very simple processes: modelling, repetition, reinforcement and association. Habits are difficult to change as ultimately, at the moment of doing any behaviour; its benefits outweigh the costs. Some of emotional triggers are in our heads such as our mood and are therefore very difficult to avoid as they follow us everywhere and are hard to ignore. Eating becomes associated with many different aspects of our environment which can prompt eating even we are trying to eat less. Some environmental triggers are physical, such as the biscuit tin, the fridge, carefully placed snack foods in supermarkets or the cake trolley at work, which cause mindless shopping and mindless eating.