What's the furthest you have ever walked in a single day? Why'd you walk that far?

15-25 kms Monday to Friday, every week for the past 8 years. I’m a meter reader, I get paid to walk. The most I did in 1 day was 33 kms. I’m in Australia so 40 degrees centigrade (over 100 F) are not uncommon. I walk whatever the weather.