https://philmaffetone.com/180-formula/

I will throw this out there, hopefully someone else will will find it useful.

Came across this website a while back and it was a big help. Walking up hills typically had me winded and needing to take a breather. Slowing down while walking was not easy at first, but it paid off in the long run. Also some great keto diet plans.

Never used a monitor (besides on a treadmill), but tried to keep breathing in check. Basically Learned to slow my pace at the start of a hill. Most of the day hikes have been in the 7-10 mile range and sometimes include some steep slopes and/or off trail hiking.

MAF

And

One other thought,

I was talking with a fly shop owner before our first trip into the John Muir, and his suggestion was that big muscles use up lots of oxygen, and are not well suited to hiking up at altitude. He thought one should be doing more of a circuit type training for walking where the air is thinner.

Totally makes sense. If you haven't been active and start going gangbusters, you will hurt yourself. 7-10 miles a day is impressive. Quite a time commitment. I suppose if I spent less time watching TV or surfing the web, I would have all kinds of time :-)