Yeah, train in the hills. That is where most suffer. As far as having fun on a ride, it is fun when you climb at a good pace rather than suffering like a dog.

Hills do slow you down though! On a flat 55 mile ride, I averaged solo 19.5. On a century with 10,000 ft of climbing, I averaged 14.0. Big difference!

Ride elevation profile!....http://www.caltriplecrown.com/Centuries/Bear.htm