I've learned a few things over the years about getting prepared for travel and hunting. The sheer length and hardship of long distance travel is difficult even for the young and fit. Also living at altitude helps if going to lower altitude. I've lived at 7600 for the past 24 years and much higher, at times, prior to that. Those who live at sea level and plan on hunting at any significantly higher elevation need to spend more time and effort getting ready.
At 74 yo and 6-3 190, I can completely commiserate with those who are long in years or tall or large. I have to ignore the advice about "just get business class"... ya right!... at 3-5+X the price of regular economy, I might as well not go at all or go once every 10 years! Crap advice for regular people on limited budget.
Getting in shape or staying in shape helps tremendously for long distance travel. When younger, it would only take me a week or two to get ready. Now much longer, more like a month or two. I had my L4 disc removed in 1988 and had problems with the L5 in 1994. I feared lifting heavy loads or carrying heavy backpacks for hunting. I learned nothing to fear if I stayed in reasonable shape. I also learned that keeping
upper body strength is the key to mitigating lower back problems!
I am currently working on getting ready for a long flight and travel. No strenuous hunt planned on other end, just getting ready for the long travel. Many emphasize diet and certain work-out plans... I don't know? I just eat reasonable foods in good variety and get good exercise around my place year round. Shoveling snow and running a chain saw and bucking heavy tree sections and brush is good for upper body strength! Brisk walking is always good. If panning packing game out or that type thing, I'll put a sand bag in my pack and do the same walking, working up to ending the prep at least 3-4 days before departure.
In a couple of weeks I'll be heading out on a long trip, but not hunting
Currently walking a lot. Looking forward to partaking in some "health food" cuisine at the local 'Bee, spending a little beach time in the shade with an ice cold San Miguel- not a tourist in sight and doing some swimming