Musicman,

I used to send my wsife crazy when things seemed at their lowest ebb by breaking into a few bars of "Even when the darkest clouds are in the sky/ you mustn't cry and you mustn't sigh/spread a little happiness as you go by" - another 40s number called, I think, Mr Cinders.
But khandu, life isn''t easy, and at times it can seem particularly shitty. But the fact that you're here, and that people here care for you, is a damned fine reason for staying away from that bridge! And, speaking personally, there's always something pretty vacant and bland about people who are perpetually bloody cheerful.
Take the cabinet-maker's view and think of yourself as like a piece of fine timber, say a well-figured piece of walnut.
What makes it so fine is that all the grain and figuring is the result of years of adverse conditions; each showing a storm weathered or a season endured. Growing in perfect conditions, the wood would be bland and dull, whereas life's knocks give it its character.
At the time, life might seem shitty, even unbearable, but that very shittiness makes you a more interesting, rounded and human person.
So, even when there seems to be nothing else you should still keep hopein your heart and cherish the affection of good friends who care, even if - like those here in the'Cat - you haven't met them yet in person.