I think the approach to hills is at least 60% mental. If you approach a hill with a negative attitude, you may well be beaten before you even start the climb. My approach to hills when I encounter them (which is frequently as I specifically look for them) is that I want to totally own them. Contrary to popular belief, arrogance isn't necessarily a bad thing.
As far as the improvement side of things goes, it's one of those things that can sneak up on you, and surprise you. You might do a particular hill for three months and notice no visible improvement on it, then one day all that practice will pay off at once, and you'll nail it. You just need to give yourself a chance - and the best way to improve on hills is to ride more of them.
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I am clinically insane. I am proud of it.
That is all.