Wear in your hiking boots
Talking through your nose will not help you.
Only other thing I can say is don't panic too much regarding gear, what you don't have you probably don't need. And seeing as you are getting fit I may aswell include some lengthy extreme hikes in the agenda
There are levels of fitness and I am seriously concerned as to how much hiking we will be doing because my ankles and knees are no longer in showroom condition with my arthritis so we may have to include a horse or something I can use to keep up with you. It's not my lungs - its my legs!
Gear wise I think I am OK. Not the best glass in the world but should have most things covered with the 4 lenses I have. Widest I have is 18-105 so may be a bit short for those lovely star shots you are going to teach me all about. I do have a 35mm 1.8 prime ???? Time will tell.