Just joined you, @Former-Member, @Former-Member and everyone. Had no email notification, despite being tagged. In fact I had no notifications at all for hours. Now suddenly my inbox is full. No matter, I'm caught up on the discussion now anyway and find it very interesting.
I am another not fond of the saying 'whatever doesn't k-ill you only makes you stronger'. I've often thought, in my own experience, 'but it can cripple you'.
On the other end of the spectrum, I speculate that growth in general can apply to any kind of suffering in a way, whether it be mental illness in a broader sense, physical illness, many kinds of life events and conditions. Suffering does seem to lead to empathy in many cases, though not all, of course.
Aside from empathy for the suffering of others, I think too our own suffering can lead to a more philosophical outlook on life. Instead of wondering 'what could I have been?', I tend to ponder more about how mysterious life is, how unpredictable, how more interesting because of that. How it is a journey. In that sense, I think I may have grown from my own illnesses, mental and physical, in a way that could be described as spiritual.