In the book of Ephesians 6:10 states "Finally, my brethren, be strong in the Lord, and in the power of His might."
The above instruction wasn't addressed to ministers of the gospel, but to the body of Christ. The apostle was saying, after all said and done, you've got to be strong in the Lord. A lot of believers love to tag themselves as weak but Paul's voice still rings clearly today: - "Be strong in the Lord."
He knows that a lot of people are quite strong in many areas of life; try as you may, you can't outsmart them in Business, Calculations, Passion, ... but are zero when it comes to the things of God.
Listen beloved, everything will pass away with time; the only thing that will outlive us will be the things we were and did for the Lord. And so, being strong is not something we choose to be or not; it is the only state that ensures that we go through life in one piece.
Battles are on going whether we are awake or asleep; they continue whether we are aware of them or ignorant of their existence. No one wins battles on their own without God's backing and input, so, we are once again brought face to face with our only option- "be strong in the Lord, and in the power of His might."
When Saul was faced with a dire situation in 1 Samuel 28, he resorted to consulting a witch because he had nothing to fall back to. 1 Samuel 28:5 says, "And when Saul saw the host of the Philistines , he was afraid, and his heart greatly trembled."
When fear takes over like it happened to Saul, the rest is history. Saul died in that battle.
David was also confronted with a bad situation in 1 Samuel 30. "Then David and the people that were with Him lifted up their voice and wept, until they had no more power to weep." (V:4) The people even spoke of stoning him but in verse 6, ...David encouraged himself in the Lord his God."
That is how to be strong in the Lord: relying, waiting and trusting Him because the battle will always be the Lord's.
Be encouraged knowing that as with God, you are stronger than your struggles and fiercer than your fears. Remain Blessed