First thing on the list - drink up! You are bound to sweat so it is crucial to constantly hydrate yourself especially in this merciless Singapore weather.
We are pretty sure you wouldn't want to hold on to your bottle the whole time during the walkathon so we recommend getting a hydration bag!
Just drink on the go and free your hands to take pictures. Plus point - Decathlon's hydration bags have small compartments for you to keep your essentials!