Hyphen or No Hyphen?

Should I use a hyphen in between life and changing in the phrase "life-changing" ?

W.

The hyphen is used to signal a compound modifier. No hyphen is needed if no noun is being modified. For example:

"This is a life-changing moment!"
The moment is neither life, nor changing. It is life changing.

"That radio broadcast was life-changing!"
Though it is at the end of a sentance, the linking verb still links it back to the noun (radio broadcast) and it still needs a hypen.

I'm not sure if there are any instances in which it wouldn't be hyphanated, but be sure to look out for them!
I know this is old, but I felt the actual reason for the hyphen should be posted.

-Dave