Okay, so, it's about to get Hot and Humid in the USA, so I'mma spring my tried-and-tested Hydration Elixir! For this recipe you will need:
Warning: DO NOT drink Hydration Elixir by itself! This is an elixir meant to be mixed in small quantities with a regular-sized glass or bottle of water! You're making the equivalent of a family supper-sized quantity of elixir, not an individual meal.
Step 1: Take a lemon, cut it in half, and juice it.
(Substitute Step 1: In the event of no lemons or inability to juice one, measure out a quarter cup of lemon juice.)
Step 2: Set lemon juice to side.
Step 3: Boil approximately two cups of water, then mix in a generous tablespoon of salt.
(note: boiling the water makes the salt dissolve fast with minimal stirring, and that is why we're doing it)
Step 4: Allow salted water to cool.
Step 5: Mix lemon juice into salted water
(note: Mixing the juice and water together when the water is hot makes the whole thing taste worse later)
Step 6: Pour your newly-crafted elixir into a bottle or jar with a lid, then put in fridge to cool.
Add a teaspoon or so of Hydration Elixir to a larger glass or bottle of water when you have been sweating to help replace salt lost due to said sweat. The lemon juice adds some nice vitamins and a pleasant taste to make it all more palatable.
Use Hydration Elixir in moderation, you've just made enough to last you a week or so, with enough to share some around with friends. Quickly drinking a concoction that consists of two cups of water, a lemon's worth of juice, and a tablespoon of salt will clean out your innards but good, and you will survive but it will be with Regrets.
Again, Hydration Elixir is meant to be mixed with a large quantity of plain water. The recipe is as it is because it's easier to quantify how much of each ingredient (especially the salt) to use for a bulk batch and how much of the batch you should probably take than to give measurements for a single glass of the stuff.
Plus, if you've got it already made and chilling in the fridge, then you just need to plop a teaspoon into a glass of water when you've come in hot and sweaty and tired or mix some into your water bottle to take with you before you head out.
Stay safe and stay hydrated!