Keeping alert for an attack of some kind by Forrest.

But if you don't want the same fate, you'd better keep alert.

Now all she needed to keep alert for was attack from above.

She had to keep alert, try to remember the way they were traveling.

We can stay well to the shady side and keep alert.

"No one has to be told to keep alert, do they?"

There was no need to tell him to keep alert.

But she knew it could be dangerous, and kept alert.

He would advise his soldiers to keep alert at all times.

It was requiring more of an effort for her to keep alert.