Frist, you have to edit an RPG map. Take whichever.

Next, just add hp and/or strength potions wherever, I recommend close to spawn point, on big and empty fields.
You can add how much you want. If you wanna have almost immortal character, just add hundreds.

Save as RPG map, better if name will be another than the name of original RPG map.

Just play this map how many times you want, drinking those potions.

In-game it's not cheating, but be aware that it's not fair so I think it's cheating :)

I hope it helped you, if you have any questions, ask in comments.
If you want to play online, just invite me on Steam.

Thank you all guys for reading!