For me the best physical preparation for multi-day hiking is … hiking. 

On arrival at the trailhead, start with shorter, easier days. Work up to your normal pace. Progressively.

Off-season I cycle and run. 

BEST of all for me, however, is running stairs. I have done sets of 10 with a day pack in the past, as well.

Click PLAY or watch it on YouTube.

In Calgary, I often ran the stairs at nearby Glenmore Park.

Click PLAY or watch it on YouTube.

https://besthike.com/2024/01/0...