"Weak" is such a relative, personal perception. A broken arm is "weak" too but bones don't generally get broken by soft forces acting upon them? I'd ask people who thought anxiety or depression meant a person was weak to consider what had to happen to those people to get in that state. Babies generally aren't "anxious" or depressed yet and toddlers/little children who are, it's usually obvious they started with some sort of genetic predisposition so that's not their fault either. People who "become" anxious or depressed, usually fall out of a few trees and get broken and battered in some way?