I've gotten lots of good advice over the years but most recently... to relax and take a rest while climbing up hills. OK what does that mean? It means use your low gears, start out slowly and comfortably and once you hit a nice cadence, pick it up slowly. Near the top you shuld have enough left to stand and dash (or on a mountain bike, pick up the cadence and push). I used to rush the hills and peter out towards the top. No more!!! I used to avoid hills and now I seek them out. I eat hills for breakfast!