Cross-Platform Fitness App Development

I'm seeking an experienced mobile app developer to create a comprehensive fitness application for both iOS and Android platforms.

Key Features:
- Focus on workout tracking, nutrition planning, and community engagement
- User authentication via email and password

Ideal Skills:
- Proficiency in Swift (iOS) and Kotlin/Java (Android)
- Experience with secure email/password authentication
- Background in developing fitness or health-related applications is a plus
- Strong UI/UX design skills to create an engaging user experience

Please provide examples of similar work done and estimated timelines.