Closed mouths don’t get fed.
I’m not sure when I started to internalize this or where I initially read it. But, it’s something that has stuck with me for some time.
Phrased differently, one might use:
You don’t get what you don’t ask for.
What’s the worst that can happen? You get told “no”?
But, I’ve always preferred the imagery of the former, which evokes a sense of urgency for me.