One of the most consistent themes of Scripture is the reality of suffering in the Christian life. I find this ironic in the fitness community because this is a reality for an athlete in day-to-day training. Suffering produces results. We know this to be true about training. We can't look at the top athlete in any sport and not immediately see the presence of suffering in their day-to-day training. Sure, genetics and talent play a part in their success as an athlete, but nothing comes without work. That work brings about the kind of suffering that creates adaptation in your muscles and in your body's physiological systems.
The same is true for our growth towards the Lord. The Bible consistently reminds believers from Genesis to Revelation that Christians who are truly living out their faith will encounter suffering on a regular basis. Read Romans 5:3–5, or Psalm 34:19, or Matthew 5:10. God promises suffering in this life. What we have to wrap our heads around as Christians is how we embrace or run from the suffering.
I find it immensely ironic that most athletes will run to suffering knowing that the results produce a desired effect in their performance. Yet, in our Christian lives we will run from anything that causes suffering or compartmentalize God to a place where we avoid suffering altogether not realizing we are missing out on the resulting effect on our holiness and our faith. Suffering isn't something anybody wants to create for ourselves. Nobody walks into the gym saying they're looking forward to the wear and tear on their muscles, the pain of training, or the soreness that comes the next day. However we are excited about the result. The same should be said about our lives with Christ. Creating suffering is not our calling but enduring suffering with gladness and rejoicing is. For a little deeper look into this idea take a look at John Piper's blog from yesterday here.