"They didn't want people with the old ways of thinking because they knew it was a really challenging mission," she said.

Well, he could remember feeling the same way himself once, when he'd been assigned a challenging or exacting mission.

The Navy is prepared to pay for its most challenging and risky missions, if the price is made clear at the outset.

This will be our most challenging mission, and perhaps our last if we succeed.

"This is a more challenging mission than what I've done on my previous three flights," Captain Lawrence said.

General McCaffrey, for his part, said it was an achievable but challenging mission.

Now, he said, planners are trying to do too much by mounting unusually challenging missions within arbitrary schedule and cost caps.

He carried through this challenging mission with untiring energy and dedication even at the risk of his career and death threats.

Goes on an adventure with challenging missions while gaining skills in physics and engineering.

So the marines want to make sure that their detention center is secure, a task which makes it difficult to undertake another challenging mission.