My kids only come around once in my lifetime, and they (hopefully) won't be with me forever. I chose to have them, and I choose, freely, to make them and my family a priority in my life. This stage of life won't last forever. While it does, I've climbed on for the ride.
Sometimes, in that darkness, there is a single act of love, some selfless gesture, an aspiration, and we see that it's not been all waste, all hopeless, and we can. . . well. . . go on.