A: You look very much exhausted. What’s up?

B: It’s mostly work. Production at my factory has gone into overdrive in an attempt to meet the new orders on time. I had to put in overtime everyday for the past week.

Note: This idiom means “to start working very hard or quickly.” Overdrive is an extra high gear in a vehicle that you use when you are driving at high speeds. Earlier it was a transitive verb, meaning “to drive too hard, work to exhaustion.” You can also say that someone or something is “in overdrive.”