How can I click "Do It!" button with keyboard? This was been question for a long time for me.
How can I click "Do It!" button? Do-It button means, a button will trigger destructive changes. So usually, that's not default button, and I don't know how to click it with keyboard.

I'm asking this because I got a real fantastically suiting situation for need of this.
If there's just one option hitting Space or Enter should do the trick, as the button should be preselected. If there are more than one option you could tab between them by enabling  All Controls under System Preferences / Keyboard / Full Keyboard Access. 

When tabbing through, a subtle blue glow will highlight the tabbed component. Hitting Space will use it, while hitting Enter will use the default option.