What kind of bike are you riding?
What kind of tires are on it? Mountain? Road? A hybrid tire?
Is the seat adjusted well?
Are you heavy? > 250#
There are a lot of variables. Sometimes it just takes conditioning. A few years back I was riding up a grade that used to kill me and I passed someone struggling along. He was on a road bike and not overweight. He commented that I should at least act like it was hard for me. He was a newer rider and I wasn't. I was better conditioned. The day will come when he will ride the grade without a problem.