This datapack makes Minecraft a lot more realistic
Extract this file into your datapacks folder and type /reload ingame
If a thirst bar appears at the top of the screen you have done it correctly

You need to drink water, milk, or melon slices to keep the thirst bar up.
If it gets down to zero you will take wither damage

As well as that, if you punch down trees with your hand you will take damage, as with walking on gravel in bare feet
If you kill a villager you will be imprisoned in a bedrock prison (you will stay in there until you find out how to escape. There is a way)

When you take damage you slow down a bit

Fishing now gives you a lot more exp

If you wear any kind of netherite armour it is so heavy it will slow you down

EDIT: There is a bug that the bossbar disappears when you relog. Use /reload to get it back again