Design a database schema for a fitness app.

A robust fitness app database schema would include tables for Users (storing user ID, credentials, contact info, and account creation date), Exercises (cataloging various activities like running, cycling, swimming with unique IDs), and WorkoutSessions. The WorkoutSessions table would link to Users and Exercises via foreign keys, and also record session-specific details such as date, start/end times, duration, distance covered, and calories burned. A Dates table could be used to store date components (day, month, year) for efficient querying and reporting, linked to WorkoutSessions by a session_date_id.