Happy in My Heartache Lyrics

Lyric discussion by charcola 

Cover art for Happy in My Heartache lyrics by Josh Groban

I can't find a reason to be happy in this heartache 'Cause I should know better than that

I'm not entirely sure what he means here, does anyone know / have any thoughts?

I would imagine it is as simple as his heartache is great enough that he is unable to find a reason to be happy.