Worrying is all about the What Ifs in life. In particular what if things go wrong? The mind likes to have resolution and keeps trying to answer these questions. However the majority of worry is things that are out of our control and they are in the future. What if we change the way we ask ourselves these questions to be more optimistic?
What if nothing bad happens? What if I like what happens? What if this thing is an improvement?
The mind can rest if you have an answer or at least a plan. If the plan is to do your best and leave the rest in God Almighty's hands, then perhaps you can sleep.