What are external influences on physical activity. I need someone to list two influences. Please help me.

Many1. why should teens be aware of health issues such as healthy sexuality, dealing with conflict, healthy decision making and cpr? 2. a) what are the 3 most important aspects/skills to learn in order to play volleyball activity well? b) explain how each aspect/skill is important when playing the game. c) describe 2 points of strategy you could use to you be successful at this activity.