A Sense of Scale.

It is vitally important that your pcs posses a sense of scale. Sometimes they will have phenomenal cosmic powers and great wherewithal but feel like an underdog or downtrodden or put upon because they are up against far greater threats. From time to time put in a few under challenging encounters. Have them beat up a few random thugs. My personal favorite is a homecoming scene in which they have to go back to their starting area and deal with the problems that seemed so insermountable a mere few hundred experients points ago. It helps keep everything in context. When you're building a mood or trying to maintain suspension of disbelief, context is king.