You Gain Energy From Sleeping Or Doing Fewer Things Such as Destroying blocks placing blocks, running, walking, etc., and Eating Something Will Give You Energy, Tip: Honey And sweet things give more Energy.

You Will Start To Be Tired When You Do More Things Such as running placing blocks, etc.,

When Energy Is Low You are slower, And Then Blind, Then At 0 Energy You Will Be poisoned

When Energy is high you walk faster and jump higher and even more vital when you have a lot of energy

You Can Change The Energy Bar Color Or Style By Typing "/reload" and then clicking on the color or style you want.
The ResoucePackStyle Requires you to download the resource pack(You can download the resoucepack below the datapack download button).

to uninstall type: "/function energydatapack:uninstall" (It Does Not Uninstall From Computer, It Only Removes All scoreboards And datapack stuff and disables the datapack(You Can Enable it With /datapack))

The Datapack Won't Immediately Remove 1 Energy When You Run, Only After You Do More Things, Or If You Run, The Same thing For When You Get Energy, I Actually Made 2 Scoreboards - 1.Energy+, 2. Energy- And When You Run And Do Things Energy- Will Get Points,
When You Rest, Sleep, and Eat - Energy+ Will Get Points, At Some Point, The Points Of The scoreboard will convert to a +/-Energy Point, There's Also More Scoreboards&Things Such As a Sleep Scoreboard When You Sleep You Gain 10 Energy Points.