How time flies

I can hardly believe that today I have been in my job for 35 years.

I often have patients say to me "you've been here a long time haven't you?"
To be quite honest it doesn't feel that long as the job itself is constantly changing.
I counted up the colleagues I have worked with over the years and got to 21 dentists and about 40 nurses, there were just one or two I could picture but whose names I could not recall.

Maybe they didn't stay long enough to make an impression - impression get it?

Never mind - it's a dental joke.