It's also important to note how important positive behavior is on those around you. One thing I've learned since programming professionally is that it's a team sport -- doesn't have to be, but in most cases you'll develop along with others. When you develops habits of cynicism and negativity it spreads. To those junior, to your direct peers, and especially to non-technical teammates.

I've found that by setting a positive tone, especially in somewhat negative situations, speaks volumes. Cynicism is easy. Pushing those feelings aside and remaining stoic in tough times helps tremendously.