Personal Trainer Website

Hello,

My client would like me to build a website.

It will be a subscription type website – once you sign up you will have access to a personal training program that gives you daily workouts to do, you can tick these off each day, it will have the option to send email reminders too. You can add in your current weight and track your progress. There will also be page full of videos and documents that, once you have signed up you will be able to read/view.

The admin of the website will be able to manage all the clients and track their progress and chat/give advice to them.

So my question is – how shall I build this? I am familiar with WordPress but just need to know where to start really.

Would really appreciate any help!!

Thank you