The luck of the draw
Definition 1 of 1
Pro Tip 1/3Common Saying
This phrase is widely recognized and used to express accepting outcomes that are uncontrollable. 
I didn't get my preferred schedule, but it's the luck of the draw.
Pro Tip 2/3Neutral Tone
The phrase is used neutrally, not to express happiness or unhappiness, just the randomness of life. 
I guess taking the last slice of pizza was just the luck of the draw.
Pro Tip 3/3No Blame
Use it to indicate that a result is not due to anyone's fault or intention; it's random. 
The raffle winner is chosen by the luck of the draw, so don't be upset.