No question hills are the hardest thing. Where I live, most rides require dealing with several miles of 4% grade. Not steep, but not easy either, especially when new to cycling. My first rides were just riding uphill probably 1/4 mile. Then downhill to home. Progress occurred quickly. I was able to go further every ride (every other day). Since uphill was toward a mountain range, it would also get progressively steeper. On these steeper areas 6% or more gradient, I would have to stop periodically and gasp for air.

But progress continued and within a year I was making all those climbs without much thought. It doesn't mean they became stupid easy, but I didn't need to be in 1st gear all the time and no longer needed to stop mid-climb or stop at the top to catch my breath.

It was about 3 months before I dared to start a ride going downhill. I was concerned I'd go too far downhill and not be able to make it home. That was a big deal at the time. now I'm almost always doing that and more and not giving it any thought.

My suggestion is work on those climbs. My first weeks I would break up a climb into many small goals. Just looking to get to the mailbox 100 ft away, then to that large weed on the side of the road, then the patch in the pavement. Looking at a long climb can be very daunting. Just set more attainable goals. But you might be surprised how you think you can't do another 100 ft, but once you finish the last, you decide to keep going. I found this very satisfying.