I learned the hard way that drinking water when exerting my (aging) body is not enough. Here is my recipe for an electrolye-replenishing drink to whip up at home.
1 gallon pure water
1 cup sugar of choice (NOT artificial sweetener)
1 packet powdered drink mix such as Kool Aid
1 tsp low sodium salt replacement
Don’t skip the sugar or the salt replacement. This is the source of electrolyte. If you don’t like using the powdered drink mix, use an unsweetened fruit juice of your choice. Lemon and lime are excellent choices. Chill and drink up.
Another good drink for electrolyte reacement is tea. Black tea is rich in minerals, especially potassium.