“How does it help to make misfortune heavier by complaining about it? This is more fit for a king – to seize your adversities head on. The more precarious his situation, the more imminent his fall from power, the more firmly he should be resolved to stand and fight. It isn’t manly to retreat from fortune.”

Seneca, Oedipus.

Complaining serves its purpose for a short while: it’s an expression of the emotions that are already running when you’re disappointed or worried or upset in some way. But continuing to complain only keeps the scab from healing over the wound. Better to channel your mind power onto the task at hand. If it’s not in your control, what do you need to do (test and adjust) now to get over the challenge?