My suggestions/ advice depends my attitude and beliefs. Those are
1. I am a leisure cyclist, meaning I cycle for pleasure. I will never ever dream of doing racing etc. So I do not keep an eye on my speed, cadence, heart rate etc. I just cycle and when I feel tired I stop.
2. Cycling helps me to eat what I want and not other way around. I don't eat to support cycling. But I have a balanced diet. I am totally against all forms of diets and nutrition plans. They are not for me.
3. I believe that mind is as important as body with regard to all activities.
4. I am a self proclaimed geek. So I have read various articles on the subject to understand the science.
Based on the above, my view is that climbing hill is an art based on science.
The science is mathematics, physics and physiology.
Physics/ maths will tell you that lower the gear ratio, easier it is to climb. So I have chosen my bike to give me a gear ratio of one. My bike has a triple, 50-39-30 and rear cassette of 12-30. If you continue to struggle, you may consider changing your gear set up.
Then there is the art of when and how to change gears. As a basic rule, you must change gears before you run out of energy.
The technique of pedalling is important to get the maximum benefit of pedalling.
Physiology will tell you that your heart needs to pump faster, lungs need more oxygen. Therefore you can adopt a posture to open up your lungs and deep breaths rather than short and rapid ineffective breathing.
With regard to the mind, you need to approach hills with a positive mind.
I suggest that you look at following youtube clips to understand what you say.
Finally, it never gets easy, you just go faster, I can't remember who said that.