For me it's a mental game. I expect some hills to be tough, so they are.
There are other hills that on paper seem to be similar, and I have no problems with them. That may partly be due to differences in pavement. Chipseal, rough pavement, uneven seams, etc., can drain energy. (For me, bigger tires run at lower pressure helped on chipseal climbs.)
Since I expect some hills to be tough, I tackle those repeatedly and try different approaches and methods. Sometimes a fast start, sometimes a more even effort throughout. Sometimes mash, sometimes sit and spin, sometimes stand and stomp the whole way up in the biggest gear I can move. Sometimes I'll combine all three. But that's mostly to break up the mental block.
Breath control too. I realized I was tensing up and not breathing properly on hills I dreaded. That just makes it worse. So I'll ease myself into the climb with full deep breaths and blowing out as much as I can on the approach, then consciously use the diaphragm and puff out the belly.
Watch some of Emma Pooley's videos on climbing tips when she was with GCN a couple of years ago. Emma is a mountain goat, but also tiny so her technique may not work for everyone -- she stands a lot to climb, and for a long distance. I had to lose 20 lbs to be able to do that. But I noticed how relaxed her belly is during climbs, puffing in and out like a bullfrog's throat. I realized I was way too tense and just chest breathing. That helped. Now my legs get cooked before my lungs feel like they're on fire. I used to be out of breath even before my legs were tired. Poor breath control.