On my first ever road bike ride, I did a 57 mile route including Holme Moss. It was a bad idea, I was knackered after 10 miles as I hadn't been on a bike for 15 years.
However, whilst I had to stop probably 15 times on Holme Moss I never walked, I got back on and pedalled every time until I reached the top. I told myself there and then I'd never walk up a hill. My will was tested soon after as I stupidly tackled Winnats Pass, I was so tired I fell off sideways into the grass without even unclipping. I got back on though, got going and made it to the top.
I've been up both those hills plenty of times since, and lots of other 'hard' hills, but now I'm pretty fit (and 68kg) nothing will ever feel as hard as they did at the point I did them.