A custom workout companion application has been built using Twilio Functions and Airtable, allowing users to receive workout routines, instructions, videos, gifs, and progress tracking via SMS messages. The application uses a Twilio phone number and requires an Airtable account for data storage and API access. Users can select a workout routine, receive instructions and visual references, and track their progress. The application also includes features such as cookie-based state management and error handling to ensure a seamless user experience.