@solderandchaos

IIRC from my Boy Scout days, average walking speed is 3 miles per hour.

One BSA award required 50 miles in 2 days.

*IF* you walk 3-5 miles daily, you should be in good enough shape.

As others have, ensure a good walking kit : shoes/boots, socks (2-3 pr), WATER, snacks¹, weather gear, NSAIDs², "moleskin" for blisters, etc.

If possible, walk fast enough to take a 5-15 minute every 0.5 - 2.0 hrs. Change your socks at least once!

I pray that you succeed!
I pray that you recover quickly & fully!

8- )

( ¹ snacks include nuts, granola, dried fruits, etc. )

( ² NSAIDs : Non-Steroidal Anti Inflammatory Drugs: aspirin, ibuprofen, naproxen, etc. ;
N.B. acetaminophen/ paracetamol does NOT usually suffice )