At age 69 and weighing 180 lbs. I am not a great climber so I need every trick I can find. And, I have actually found one that has helped me a lot. That is exhaling fully so that each inhalation brings as much O2 as possible. It has literally transformed my climbing. I'd try that with some of the other advice given here. FWIW, the conventional wisdom is that when seated you move "back" on the saddle not forward.