person A: I had a great day at work today!  We are working on some pretty complex accounting_comma_ and I've had to do a lot of prep at night. 
person B: That's really awesome_comma_ what makes it so complex?
person A: There are many different variables that need to be taken into account-- things that I don't usually deal with on a day to day basis.  But my extra prep at night has made it so that it's seeming easy.
person B: Well that's really great that you were able to prepare so much_comma_ obviously you know what you're doing! Do you usually have to prep so much?
person A: Not usually; this is an unusual case!