In a 2 day spike, I created my own Elixir-based AI Personal Fitness Trainer! The surprising part for me was how useful and helpful I found it. It helps you create a weekly workout plan in line with your goals. Information about you is stored in a local SQLite database. Report on your workouts to your assistant and they log it for you. The assistant can access your stored information and historical workout logs to answer questions and help you on your personal fitness journey! 
I put it all into the Elixir LangChain Demo project so you can run it locally yourself! Poke at the code, customize your own fitness trainer to work the way you want!
Here’s a write-up and overview of how it works along with links to the project.