That the world is a mad and dangerous place.
I went into 'Decathlon' the other day (mega sports shop chain in France, and probably elsewhere) to get a pair of sensible shoes as walking the dogs in flip-flops (me, not the dogs) had become unrealistic in November.
I located the shoe section and then had a quick wander around to look at what people actually buy under the umbrella of sport. Mostly, what one would imagine, if not a bit excessive: bikes, swimwear, fishing clobber, tents, a kilometre of ski equipment, pink girly dance wear - for men too; hiking stuff, etc, but then I ventured into the isle of SNACKS.
You go for a walk or a run. Good. What do you need to replace the water you have sweated out? Water. Bit of fuel? - banana, a handful of dried fruit and nuts?
There was an isle as long as a bus full of alternatives: yellow, blue, pink and orange water substitutes, all incased in future landfill. People must buy this stuff - lots of it, the manufacturers continually producing more effective, and more colourful ways of hydrating.
There are millions of people in this world desperate for a container of pure water, folk who walk miles every day to a stinking hole of tepid water and then return so their family can just about survive.
Jog, run, cycle, hike, but just take a bottle and re-fill it with clean, ordinary, but luxurious tap water.