I've tried to find a way to enable 2 factor authentication for login to the google apps management console (https://admin.google.com), but can't seem to find it (already have 2 factor auth for my users on the domain, so it is not for domain users but for the admin console I want to enable it)

Have googled for it and searched here also, but can't seem to find the answer/way to enable it.

Can anyone help, please?