We can take suffering to be an opportunity to learn and to grow. But if we are honest, we should remember that this is making the best of a bad job, and that minimising suffering takes priority over optimising its outcome.
Many people are never happier than when they get the opportunity to complain, while others are deeply unhappy with how things are but just accept the fact. Complaint occurs when we refuse to accept that things are wrong and we do something about it, even if that something is simply articulating our unease.