The simple answer is often to do something bold and previously unthinkable.

We've got to think the previously unthinkable.

It takes a burden off their shoulders and they can move into jobs previously unthinkable, such as teaching.

GO one step further than ditching heels - by doing the previously unthinkable and wearing trainers to the office.

Now he was walking away, putting family before his political patron, a previously unthinkable desertion.