For a health and fitness tracking app, identify which two features from the list below are potential core product-side levers that can effectively improve activation rates:
- Lever I: Integrating a feature for personalized workout and diet plans based on user input.
- Lever II: Implementing a reward system for achieving fitness milestones.
- Lever III: Enhancing the app's interface for more intuitive navigation and user interaction.
- Lever IV: Running targeted social media ad campaigns to attract new users.