I hear people use this verse for the wrong application:
Exodus 14:14 “The Lord will fight for you; you need only to be still.”
I’ve heard well meaning people use it as an indicator that, because we are on the winning team, we will never face another battle. Not true.
Here’s something you need to understand about this verse, before you try to live it.
The verse doesn’t mean you don’t have an assignment. It doesn’t mean the assignment you have won’t be difficult. It doesn’t mean doing nothing.
Consider the next verse:
Exodus 15:15 Then the Lord said to Moses, “Why are you crying out to me? Tell the Israelites to move on.”
In other words…get going! Do what you’re supposed to do! Don’t stand there in fear…MOVE ON!
The Israelites were going to cross the sea. It would be something they had never done before. Have you ever walked through a wall of water, on ground that used to be the bottom of the sea?
Seriously, have you?
The Israelites were going to have to trust God that God would part the waters and dry up the land. Keep in mind, this command was given before the sea had even started to separate. They had to believe that the water would divide. They then had to believe the wall of water wouldn’t drop and fish wouldn’t fall on their head as they drown. They had to believe that crossing the sea was a better option than surrendering to the Egyptians. It wasn’t doing nothing. It was walking by faith.
The verse, then, means that if you are moving at the direction of God…if you are following His plan for your life…if you are being obedient…you don’t have to fear the outcome. You don’t have to worry about the provision of God for your journey. You don’t have to wonder if God will do as God said He will do. He’s got your back! He’s got the ultimate victory. You can rest in Him. You can be still!
Being still doesn’t mean doing nothing!
Have you been “standing still” when you need to be moving?
Quit making excuses and act on what you know God has called you to do!
Question: "What does it mean that God will fight our battles (Exodus 14:14; Deuteronomy 1:30)?"

Source: http://www.ronedmondson.com/2012/03/being-still-doesnt-mean-doing-nothing.html

It means humbly enduring and patiently persevering.