To afflict is to cause suffering, pain, or misery. It’s often associated with medical conditions. Carpal Tunnel Syndrome is most likely to afflict someone who spends many hours every day typing on our computers.
We get afflict from the Latin word affligere, meaning “to strike down,” which is an old fashioned way of saying to get sick, or to have a condition of some kind. You could argue that chronic indecision was the main problem to afflict Hamlet, or that saying "um," "like," and "you know" are speech tics that afflict teens.