One of my most grueling rides last summer was a loop around a local lake - pretty much all hills, one after another. The good thing is that they were ONE AFTER ANOTHER...which meant using momentum from the previous downhill to make it about halfway up the next hill without having to exert too much power. By the time I realized what a big hill I was climbing, I was 2/3 of the way up it and just told myself to get it done.