Hard times create weak people. People aren't iron that gets tougher when forged in fire. People are bags of meat. People accumulate damage and damage creates scars. Scars are only "tough" in the sense that they are less easily damaged than the virgin tissue before. Otherwise, the function of the tissue is degraded in every other property.

Stress causes health issues. Particularly traumatic stress causes (wait for it) Post-Traumatic Stress Disorder. All else being equal, a person with ulcers and anxiety disorders and depression and PTSD is a less capable person than one without.