I decided when I was eighteen and flirted with Buddhism that this belief system was as good as any, and was in contradiction with none. It very nicely kept me conscious of the cause and effect of my every action, and it was elastic enough to explain the unexplainable, the great inequities of life, through the idea that souls carefully designed their circumstances before birth, chose their parents and their location and their bodies, to trigger an unfolding in that life that would allow specific lessons to be learned, karma to expiated, loved ones to be in proximity again and again.
It's a very forgiving but also exacting belief system, in that lessons that remain unlearned will simply recur. Better to learn our lessons now, rather that wait for them to ramp up in urgency. Besides, we earn karmic brownie points for the good we do in each life, and the challenges we meet with courage, and we rack up the promise of cosmic payback for the ill we do as well. According to this interpretation, we choose our lessons for each life; we choose the time when we will suck it up and learn them. That doesn't mean things that aren't in the script don't befall us once we're here in this imperfect earthly laboratory. All manner of unplanned events can derail us, because despite our careful planning before each new incarnation, we are born mostly forgetting it all. We're wandering sightless on the plain, depending on instinct and intuition and tossed about by fear and reaching always from an innate desire to love and be loved, the experience of which transcends all.
But of course, in the end, this is all story. I'm really just spinning stories here, because how can we know any of this for sure. But the sorts of stories it is possible to tell myself can help me sleep at night: For example, my cousin Pearl chose this wrecked addicted experience of a life in agreement with her mother, my beloved, now bedridden aunt, who perhaps had set herself the lesson of remaining devoted to a soul she has loved through many lifetimes, even tested to the bitterest end.