Square Wheels

"Wow, you caught me off guard," commented my surgeon after I asked him how he was doing as he entered the examination room.  It was my 3 month anniversary visit after having my Achilles detached from my heel bone for some repair work. "So seldom does a patient ask a doctor how he is doing... I'm fine, thank you for asking.  And how are you?" he queried.

Hmmm...my inner voice stalled...How do I answer this properly?