I had a great day at work today; I really killed it!
I had a great day at work today!  We are working on some pretty complex accounting, and I've had to do a lot of prep at night. 
user
That's really awesome, what makes it so complex?
assistant
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.
user
Well that's really great that you were able to prepare so much, obviously you know what you're doing! Do you usually have to prep so much?
assistant
Not usually; this is an unusual case!
user