SHORTY: May you have ease...

 I found this more helpful. "May you have ease with difficulty."

Instead of: "May you have ease." --- which is pretty good,but has a danger of creating a desire to avoid dis-ease.

Better: "May you have ease with difficulty." --- this is realistic and not wishful thinking. My goal isn't to have ease all the time by avoiding difficulty (in the outside world). My goal is to find ease even amongst the worst difficulties, aging, illness, death, loss, fear, anger.

See also The Sublime Attitudes, by Thanissaro Bhikkhu, for more discussion on the Theravada view of how to use metta for the goal of calming the mind and heart.