The pulling on the bars would become necessary at 15-20% grade or something. Or a sprint. But it would never be a frantic jerking on the bars, just sort of a supporting motion.

Below that kind of grade, just relax. And you want to do most of your climbing seated because standing wears you out. Only to change the rhythm a bit on a long climb, or relax your back muscles / give your quads some relief on a very long or hard climb.

Oh and do like Lance says: never look at the top of the hill. You only see the 3-4 meters in front of your bike. Suddenly you're up there. It's psychological, but looking at the top of the hill makes it ever so much harder.