Tackling the long runs....

Ground frost, bright sunshine, blue sky - perfect running conditions for my 11miler. the last mile or so started getting hard (bearing in mind that there are no flat roads in and around Reigate!!) but was quite chuffed about it at the end. Must sort out the music though - I've been listening to the same CD since I started running and at these long distances I end up listening to it 3 times!!! Any tips on running music greatly appreciated.