Characters have a health rating which is the number of hits they can take before being injured. Hits and Injuries are explained in more detail in the Combat section.
The general rule is small characters (halflings, small aliens, etc.) start with 4 health, medium characters (humans, elves, etc.) start with 5 health, and large characters (lizardmen, wookies, etc.) start with 6 health. In some genres, there may be giant creatures, which start with 8 health, but suffer disadvantage on all agility related tests.
To make up for low health, small characters have advantage on all agility type tests. Also, they have an extra benefit when wearing armor. See the Combat section for more information on armor.
Health can be bumped up by species or special abilities as well. For example, a lizardman will have tougher hide, so they may have +1 health. A mercenary is tough, so they may start with +1 health.
When things get tough, characters can dig deep and push themselves to succeed. This is represented by Grit. Characters start each session with 1 Grit point. As long as they have Grit points remaining, they can take advantage on any roll, but lose 1 Grit if the roll succeeds. Recover 1 Grit on a successful disadvantage roll. Characters may not have more than 3 Grit points.