Your user is going to 'use' 'thoughts' (plural). So you create rest api methods that allow a user (singular) to manage one or more thoughts (plural). So for EXAMPLE (example only) you might have the following Rest methods.
- Get a thought (by id)
- Get all thoughts (a list) for a user.
- Create a thought
- Delete a thought.
If you want the user to manage themselves then you would provide similar methods to manage the user (but not the thoughts.)