Okay guys, I Sweat! And I sweat a lot, always have. It doesn't matter if it's zero degrees or 60 degrees. Once I break a sweat it just keeps coming. Has absolutely nothing to do with conditioning or the clothes I'm wearing. Thus, I generally don't wear anything that is cotton except for my briefs. When cotton gets wet it stays wet. You need a base layer of a wicking type material and then a layer or layers of polyester or wool, or a combination of each. Wool is a great material for a shirt or jacket. Even if it gets wet it still has insulating qualities and will keep you warm. No Gore-Tex or similar material on your upper body. It does not breathe well enough. It's okay for rain gear in a duck blind but that's about it. This knowledge comes from decades of hunting everything from upland birds to elk and moose. And hunting in all conditions from sub zero to the 90's.
Years ago I was elk hunting in Colorado with a friend. Cold and lots of snow. He was wearing a big game outfit consisting of bibs and a parka. All lined with a Gore-Tex type material. I had my wicking base layer over wool pants, a wool shirt and a wool jacket. We had quite an ascent to climb first thing in the morning. By the time we reached the area we planned to hunt we had both worked up quite a sweat. My clothes let me breathe but his did not. By afternoon he was still wet and developed hypothermia. By the time I got him off the mountain he was one sick dude.