I'm overweight (a little) and I do lots of climbing rides. I love the mountains on the road or trail and can't imagine riding without hills. That being said, I do suffer more than the people I ride with but I do pretty well considering my 210 pounds and 52 years. What works for me is staying within myself, I can't keep up with 135 pound climbers, so I have to let them go and find my own pace. I use low gears and just try to finish the climb without blowing up. Having said all that, the best things you can do to improve your climbing is to climb lots, and, of course, lose weight.