Impulse is etymologically related to False. Impulse is a synonym of Spring. Spring would make you want to Hike. 
Enthusiasm is a type of Excitement. Excitement is a synonym of Fever. Fever is a type of Illness. 
False <--EtymologicallyRelatedTo-- Impulse <--Synonym--> Spring --CausesDesire--> Hike 
Enthusiasm --IsA--> Excitement <--Synonym--> Fever --IsA--> Illness 