Fortitude is the measure of your physical resilience.

Fortitude Levels

1Fragile Health: You aren't very durable or healthy but at least you are alive. Deal 200% head shot damage and have a 5% chance to dismember with fists and machine guns.
2Sickly: You feel a little better than you used to. Deal 210% head shot damage and have a 10% chance to dismember with fists, and machine guns.
3Unhealthy: You continue to defy gravity and keep standing. Deal 220% head shot damage and have a 15% chance to dismember with fists and machine guns.
4Weakened: You are starting to feel like normal people. Deal 230% head shot damage and have a 20% chance to dismember with fists, and machine guns.
5Hardy: You are in good health. Deal 240% head shot damage and have a 25% chance to dismember with fists and machine guns.
6Very Healthy: You are very healthy. Deal 250% head shot damage and have a 30% chance to dismember with fists and machine guns.
7Vigorous Health: You have vigorous health. Deal 260% head shot damage and have a 35% chance to dismember with fists and machine guns.
8Resilient: You are as resilient as they come. Deal 270% head shot damage and have a 40% chance to dismember with fists and machine guns.
9Amazing Constitution: You have an amazing constitution. Deal 285% head shot damage and have a 45% chance to dismember with fists and machine guns.
10Exuberant Fortitude: You have exuberant fortitude and can put a beat down on a tornado. Deal 300% head shot damage and have a 50% chance to dismember with fists and machine guns.