You can do it. It's not an impossible goal. Get it in the lowest gear, keep your cadence even, or slow it a little, and try not to stare ahead too much. I know I get myself into a "zone" when doing this kind of climbing. I've only been defeated twice (once quite recently, so it happens to all of us) and both were a sustained mile of 18-20% grades. Since there is a spot on my driveway that is 15%, it's all relative. Just keep trying and eventually you will do it.