Demoralize often implies strong emotional effects, such as feelings of defeat or loss of spirit. The constant criticism demoralized the artist, who then struggled to paint.
Pro Tip 2/3
Not Physical
'Demoralize' is about affecting morale, not physical strength or ability. Even though the athletes were fit, the harsh weather demoralized them.
Pro Tip 3/3
Power Dynamics
It can be used when a person or event has power to undermine others' confidence. The CEO's resignation demoralized the entire staff.