Concern was a feeling of sympathy for someone or something.
In 2368, while speaking with Worf, Commander Kieran MacDuff said, "I am concerned about completing our mission, ending this war. In victory. We may soon face a critical moment. The success of our mission may hang on a split-second decision. A hesitation would kill us all, and those that are counting on us will surely die as well. We cannot let this happen. That'll be all." (TNG: "Conundrum")