I'm 6'4" and 210.
Ride as many hills as you can bear.
Just as important, find your best sustainable cadence/gearing for the hills.
Since it's the thing to do these days, I tried for a long time to "Lance Armstrong" my way up the longer hills, trying to keep my cadence between 90 and 100. This was okay for short climbs, but longer climbs were still killing me.
It wasn't working because, in the end, what us big guys have going for us is strength. I lowered my "climbing cadence" to 80, and suddenly I was able to maintain this on those 2-mile climbs, and still have something left in the tank for when the grade kicked up into the "brutal" range (which I consider anything above 12 or 15%). This may never make me the fastest guy over the hills, but it gets me there.
Never, ever think about how slow you're going or how far it is to the top.