For those who drink a lot of water and try to drink 1/2-1 gallon of water a day… how???

I drink 1/2 a gallon every day (well try) and by my last few glasses It starts to hurt going down.. like a sharp pain in my throat. I also get nauseous because I’m so full of water

How do you drink that much water without it affecting your sodium levels or anything else?

I get so nauseous and light headed!!