There are many factors that influence health such as: genetics, behavior, environment, and social factors.
Regarding mental health- social media and the stigmas being pushed by big
companies definitely have a negative influence. A positive influence would be doing self-fulfilling activities (hobbies).
Regarding physical health, there are definitely positive and negative influences that impact a person greatly. Access to resources like healthcare could help someone who is privileged to have access to it averse to someone who does not have access to good healthcare.