Punchpass offers a custom link that you can use to tie an external training or nutrition plan to a customer's record.
So, you can set up a custom plan for a customer in an online tool (such as Google Docs, Dropbox, etc), & add the link to that plan to the customer's account. This link will only be visible to users with Administrator and Restricted-level access to your account. Here is more information on setting instructor and user levels.
How to Add a Custom Link to a Customer Account
In the customer's Info tab, click Edit Info to add the document to the Custom Link field.
This gives you a lot of flexibility with the design of your training or nutrition plan.
Many web-based document storage tools will allow you to share directly with your customers too, so you and your customer can both view and/or update the doc ongoing (if that's what you want to do).
Adding links to Google Documents
To find the shareable link for a Google Doc, Spreadsheet, or other item in your Google Drive, navigate to the file and press the Share button.
This opens a pop-up window, where you can adjust who can access the document and copy the link. If you're updating the document access, make sure you click Done to save your changes.