Keep a notebook/diary.
Record anything that takes your fancy: a view, a girl, an event, an emotion...anything that just makes you sit up and notice.
Then note any extreme emotions you feel and why.
John Lennon's bird when he was't with YOKO said he wrote early in the morning and late at night but only when he was upset at somethings.
As an example, I intermittently write poetry but only at 'big events'. Poems I have written have been about the death of two cousins trying to save themselves from drowning, the passing of a well loved old man and as surprise love affair between two friend that turned out well. Amazing what inspires when you look!