I have developed the expectation that ‘unbearable’ periods in life, once past, will become, with a little nudging, memories of accomplishment and growth. As such, they actually become pleasant as memories. This may take years, and I must make a point of recognizing the personal growth attained. I do not wish to repeat the dismal, wishing-desperately-that-I-would-die-now interval, but I also do not wish not to have gone through that. And so I am cheerful in the way that I am.
It is a happiness about being an adult. The moping of teenagers is partly because they haven’t had the chance or skill or cerebral cortex to turn lengthy but temporary misery—a broken heart, marital turmoil, hard study, etc.—into memories without which it would not be possible to be happy in this way.
Heck, with life insurance premiums rising alarmingly due to age, I almost wish I could go through all the agony again, but as a skilled adult rather than a child or teenager or very young adult.
Luckily I don’t have that opportunity and so don’t actually have to make the decision. (Although I don’t think my wife would go and I wouldn’t want to leave without her, so actually the decision is made and I would stay here. Sigh.)