I,m a big heavy old guy and always struggle on steep hills. I,m pretty fit, carry little fat but my weight is a handicap against the lightweight guys on their lightweight bikes. I have to accept that and have my own system. I rarely look up on a hill and just focus on the road in front while thinking of anything else bar cycling. I try to get , in the zone. It works for me and so does, the more hills I climb, the better I become. Lowering the gearing means I spin more which means, for me, my lungs seem to be working harder and my muscles less which seems to be a trade-off on which will give up first.