Mood is the opposite of Good. Good is related to Hope. Hope is related to Optimistic. Optimistic is related to Positive. 
Effect can cause/lead to Happen. Effect is a synonym of Affect. Trouble is a type of Affect. 
Mood <--Antonym--> Good <--RelatedTo--> Hope <--RelatedTo--> Optimistic <--RelatedTo--> Positive 
Happen <--Causes-- Effect <--Synonym--> Affect <--IsA-- Trouble 