2 Timothy 4:6-8
For I am already being offered, and the time of my departure has come. I have fought the good fight. I have finished the course. I have kept the faith. From now on, there is stored up for me the crown of righteousness, which the Lord, the righteous judge, will give to me on that day; and not to me only, but also to all those who have loved his appearing. (WEB)
When Paul talks about having fought the good fight, what exactly was he referring to? Well, let's first talk about what it wasn't. He wasn't referring to fighting a battle in his own strength. When he asked God to remove his 'thorn in the flesh' earlier in his Christian life, we know that he received a revelation of the power of weakness (2 Corinthians 12:1-10). So he definitely wasn't fighting a battle in his own natural ability.
He also wrote the following in 2 Corinthians 10:4-5... for the weapons of our warfare are not of the flesh, but mighty before God to the throwing down of strongholds, throwing down imaginations and every high thing that is exalted against the knowledge of God, and bringing every thought into captivity to the obedience of Christ; (WEB). So definitely he wasn't using weapons fashioned in this world to wage war.
So who fights the battle? From many Scripture references, we know that the battle is the Lord's. In Exodus 14:14, God told the Israelites that they only needed to be still and He would fight for them. In Ephesians 6:10 Paul says... Finally, be strong in the Lord, and in the strength of his might. (WEB)
In my own opinion, I think Paul was fully aware that any victories he would obtain would not be accomplished in his own self effort. When he refers to fighting the good fight, I believe he was talking about simply not giving up, knowing that the One who began the good work in Him promised to complete it (Philippians 1:6).
If you are feeling battle weary and discouraged, my prayer for you today is that you would know that 'in Christ' you are more than a conqueror. May the revelation of God's love sustain you today knowing that God hasn't asked you to fight a fight where He leaves you on your own. The battle is His. The weapons come from Him and in your weakness, Christ's strength is perfected.
Yahweh will fight for you, and you shall be still.” (WEB)