Timezone variance and how long before you return to your Timezone plays a factor.

Zinc likely helps.

Timeshifter is a good app for long trips.

Sun, smiles, water, exercise, and rest.

Although I flew 22 hours once although I luckily scored a lie down bed, and I waited a few hours to get into my room but I cranked out a solid outdoor swim. I used an exercise band on the flight for circulation and I wore compression socks.

I was ‘down under’ 4.5 days and around day 2 it felt like I hit a wall for a bit, otherwise I was fine. The jog along the ocean also helped.