NAP and VPN Question

Hi,

I have been trying to set up VPN access so that our users can access their files from home. I followed this tutorial:

https://technet.microsoft.com/en-us/library/dd182017.aspx

The VPN is working and I am able to connect, and access the files, however as these are non domain computers, I would like to be able to do a health check to make sure they are compliant. I followed all the steps in the above link, but my health checks are not being enforced. Is it possible to enforce client health checks on non domain computers? Am I missing something simple?

Thanks,

Chris