Both social and individual factors play a role in shaping one’s diet and exercise habits. A total of 62 heterosexual couples reported on health behavior values (HBVs) and completed daily diaries assessing food intake and physical activity relative to their own normal behavior and the helpfulness of health-related influence from their partners. Repeated measures dyadic analysis showed that men in couples with high average HBV ate less than usual in response to positive partner influence. Also, in such couples, normal weight men engaged in more physical activity when positively influenced by their partners. However, normal weight men in couples with low average HBV engaged in less physical activity when influenced by their partners. Women who valued health less than their partners responded to partner influence by eating healthier. These results highlight the importance of considering both social and individual contributors to health behaviors.