How to get to Environment Variables from Run
Press Start, type Path, and click Enter to select Edit environment variables for your account.
I know its not strictly using run but it works and literally takes less than 2 sec.
Try using this: "C:\Windows\system32\rundll32.exe" sysdm.cpl,EditEnvironmentVariables
For more details check these links: [1] and [2].
You can shorten your path
- by doing
Run... -> "SystemPropertiesAdvanced" - or press WIN+R and then type
SystemPropertiesAdvanced
that will bring you two steps closer.