"Therefore, having this ministry by the mercy of God, we do not lose heart" (2 Corinthians 4:1).
Push ups. Yes, I do them. I've done them for years. While in the US Army, they were as regular a part of my everyday life as the less than delicious food served in the local mess hall. Periodically, we were required to undergo a battery of physical fitness tests in order to track and gauge our physical fitness so that we would maintain proper readiness and effectiveness. During the push-up part of the tests, I would pound out a decent number in the first half of the two-minute trial. That second minute was spent focusing on getting as many as I could in order to maintain or beat the previous mark. Once hands or feet came off of the floor or knees came to the ground, the opportunity to continue was concluded. The last ten seconds for me was complete with excessive sweat, focus, and loud grunting. Though my arms burned and felt as though they had transformed from muscle to mush, I was determined that I would struggle through the pain, not give up before it was over, and gain strength through the process.
Paul, as he writes in 2 Corinthians, endured pain and many personal attacks to both his character and his calling. His suffering was public and gave much opportunity for dissenters to assert reason for him not being an apostle. The attacks were baseless, without substantiated evidence, yet were hurtful all the same. Paul's confidence did not come from his own achievements, accomplishments, or accolades. His confidence came from God's mercy in calling him to do this work. As long as he pleased God, pursued fulfillment from God, his strength would be perfected and he would persevere because God through Jesus Christ.
You will face moments or seasons of personal attacks. There will be days where you may feel that the harder you try, the harder it seems to persevere. Don't lose heart. When you seek to pleasure the expectations of people over God, the struggle will get the better of you. When you purpose to please God, you will find that struggle overcome by the strength that He gives you. Your purpose is found in Him. You don't need to be so quick to defend yourself, argue your efforts, or justify who you are. When your life is founded on loving Jesus, listening to His voice, and living according to HIS Truth, you will be led in a strength that will overwhelm the struggle you find yourself in. Never forget the words that were penned through the struggles of Paul's life: "His strength is made perfect in my weakness...When I am weak, then I am strong" (2 Corinthians 12:9-10).