how do i run First Aid from Recovery?

Shut down your Mac.

Wait at least ten seconds then startup while holding down the Command + R keys. From there you can access the built in utilities to verify and repair the disk if necessary then restore OS X using OS X Recovery.

I restarted in Recovery mode and launched Disk Utility but my SSD Logical Volume under Apple SSD Internal is grayed out and so is First Aid, UNTIL I selected Mount tab in Disk Utility and entered my password. I figured this out but thought I'd add to your point.

Thanks!

Repair the Drive for El Capitan or Sierra

1. Restart the computer and after the chime hold down the Command and R keys until the Utility Menu appears.
2. Select Disk Utility and press the Continue button.
3. Then select the indented (usually, Macintosh HD) volume entry from the Devices list.
4. Click on the First Aid tab in the toolbar and wait for the Done button to activate. Click on it, then quit Disk Utility.
5. Select Restart from the Apple menu.

holy crap, thank you. This is the key detail missing from the other explanations. Fixed!

THIS is what saved the day. Thank you!!