Lens Condensation

I was shooting lots of long exposures at night recently and my lense was condensating all the time. The camera had been out for hours but had only just started condensating. Is there a way I could have got rid of it out there for a long exposure?

I'm guessing it's because the camera is warmer or colder than the air, but how could I warm it up or cool it down whilst outside?

Rodreguez,
What were the outdoor temps that night?
And did they drop significantly during the shoot?
Was it very humid out?

As these can help produce condensation on the glass.
Try having the lens out in outdoor temps for at least an hour before the shoot and it might help.

http://www.naturescape​s.net/122003/ej1203.ht​m