You fight with two types of decks in Griftslands, your negotiation deck and your combat deck. Each of them has a different health bar, resolution, and health, respectively. You'll die and have to start over if your health bar hits zero, but if your character's resolution hits zero, they won't be able to trade. During the adventure, you have several ways to heal these bars.
The best way to heal yourself from combat is to visit the Grog n 'Dog bar which has the house icon above your map. Go ahead and talk to Fssh, who can sell you a drink to cure your resolve or food to improve your health. Both options come at a price. These options also have consequences.
If you have a drink you will receive the Slurred Speech and Tipsy card. When you eat the famous Fsshcakes from Fssh, you gain the Bloat card. These cards go into your deck and enter your draw pile rotation when you enter a fight or negotiation battle. To remove these cards from your deck, you must sleep or spend action points during a battle. You can only sleep during certain instances of the story.
One way to heal your resolve is to win a successful combat encounter. If you don't have a resolve on your character, a good way to get it back is to continually engage in battles against opponents rather than using the resolve you have to fight using a negotiation game.
During combat, you can upgrade some cards that you can use to heal yourself or heal an ally. You can also buy maps from Griftlands vendors, but most of these uses are one-time, so you need to spend your money wisely.
There are random events that occur as you navigate the map between destinations. During a random event, you will have a list of options, and you can either receive more health or resolve by taking additional consequences. Because these are random, you cannot rely on them to heal your character.
You will receive all your health and you will recover at the end of the day when you sleep. Sleep occurs at specific points in the story, and you won't be able to do it until you reach that point.