Complex sentence: Instead, members hold in their minds a mental image of their affinity--for example, the nationhood you feel with other members of your nation when your "imagined community" participates in a larger event such as the Olympics.
Split into simpler sentences: Instead, members hold in their minds a mental image of their affinity. For example the nationhood you feel with other members of your nation when your "imagined community" participates in a larger event such as the Olympics.