Peers are a huge part of life and affect people in many different ways. In adolescence and adulthood, peers have different kinds of impacts. The researchers chose to research how peer influence can affect the decisions, performance and attitudes of adolescents and adults. Specifically, researchers analyzed how lifestyle decisions influenced by peers affect mental health and how the effects differ from gender and age. Participants of the study were selected to fit the three age groups needed for this study and responses were collected via electronic survey. Throughout this study, the relationship that peer influence has with mental health, positive and negative activities, and age is fully addressed.