1 Corinthians 16:13 says, Be on your guard; stand firm in the faith; be courageous; be strong.
In this scripture, Paul is encouraging the people on doing the work of God. He says be alert and aware of what is going on around them(Our adversary). He also encourages them to stand firm in their faith, know who God is and what he represents. He tells them to be courageous, and go after all God has planned in purpose for them. And last but not least, he says be STRONG. As we move through life daily, it builds our muscle whether we like it or not. We don't ask for trials to enter into our path, but God allows them to build our strength and dependence upon him. It's even more important to be strong while doing ministry. God has a plan for our lives, and sometimes it doesn't feel good. We have to remain strong saints. We have to stay focused, knowing that someone needs our gifts. We have to be courageous enough to take life head on with the power of God behind us.
We have to STAND STRONG