Spiritual Fitness for the Battle Against Sexual Sin

These days, you can find a seemingly endless number of videos online that will give you helpful tips to maximize your physical fitness, and those have some value. But what about spiritual fitness, which holds promise both now and for eternity?

I’ll never forget the moment I painfully realized my body was aging. I’ve never been much of a runner, but I’ve always enjoyed sports. So, when the opportunity came to run my first ever 5k, I thought it’d be easy; I just needed the willpower to finish. As a result, I did almost no training in advance.

Race day arrived, and I casually did some light stretching. Shortly after the gun went off, I knew that exhaustion would be a barrier. What I didn’t expect was a strained calf muscle just one mile into the race. This pain was new; it had never happened to me before. But I was determined to finish. I hobbled my way through the final two miles and figured a day or two of rest would be sufficient. But that injury was the beginning of multiple calf strains and tears that plagued me for years. I was not physically fit for that race because I didn’t think I needed the work required to get my body ready.

The Bible tells us that there is a valuable lesson we can glean from physical training. Paul says in 1 Timothy 4:7–8, “…train yourself for godliness; for while bodily training is of some value, godliness is of value in every way, as it holds promise for the present life and also for the life to come.” Physical fitness is good, but spiritual fitness is essential. Here are five things to consider regarding spiritual training for the race ahead of you.

1. To Build Spiritual Fitness, Train with Others

If you’re like me, running alone is torturous. After a quarter of a mile, I’m ready to start walking. But if I run with another person or a group, I can go so much farther. The same holds true for the spiritual race of the Christian life—we were not meant to run alone.

Hebrews 3:12–13 says, “Take care, brothers, lest there be in any of you an evil, unbelieving heart, leading you to fall away from the living God. But exhort one another every day, as long as it is called ‘today,’ that none of you may be hardened by the deceitfulness of sin.”

Left to ourselves, sin’s deceitful tactics are very persuasive.

“What’s the harm in looking at porn just for a few minutes? After all, you’ve had a really stressful day.”

“It’s OK to fantasize about a romantic relationship with that person. It’s only your imagination; you’re not actually going to do anything.”

“You’ll never be accepted as you are now. But cross-sex hormones will open up worlds of acceptance from everyone you care about.”

We’re all prone to justify our behavior—including when we incrementally tip-toe into the seemingly shallow waters of sin and when we’re deluged by depravity. But God’s Word tells us that brothers and sisters can cut through those lies and bring us back to the truth. To maintain peak spiritual fitness, we need the frequent, even daily, exhortations from others to ground us in the truth.

2. To Build Spiritual Fitness, Pursue Resistance Training

If we never use our muscles, they will atrophy and weaken. The biggest spiritual muscle we possess is the muscle of faith. Faith is vital to our battle against sin, and yet our flesh absolutely hates using it. Often, the only time our faith muscles are truly exercised is when we realize that our sight muscles aren’t getting the job done.

Our salvation does not depend on the strength of our faith but on the object of our faith, Jesus Christ. And yet, this does not negate the real necessity of growing in our faith—becoming stronger.

When life is easy, the bills are paid, the body is strong, relationships are peaceful, and work is fulfilling, it’s easy to rely on sight alone. But once life gets hard, we face a fork in the road: will we walk by faith or by sight? To exercise the sight muscle in suffering means seeking a way out of suffering apart from God. And sometimes, it might seem like it’s working. But when the suffering doesn’t abate and your sight muscles aren’t cutting it, we are prone to justify sinful escapism to take the edge off. We look for anything we can see, touch, taste, or feel, here and now, to make us feel better.

What about the muscle of faith? I think many Christians try to exercise this muscle in suffering. But because it’s rarely been used, it feels utterly inadequate for what they’re facing. They try to pray, read Scripture, wait upon the Lord—but all those practices feel anemic in the moment.

Our salvation does not depend on the strength of our faith but on the object of our faith, Jesus Christ. And yet, this does not negate the real necessity of growing in our faith—becoming stronger in faith. We see many exhortations to grow in faith in the New Testament. Both the apostles and others asked Jesus to increase their faith (Luke 17:5, Mark 9:24). Paul was grateful to hear that the Thessalonian believers’ faith was growing abundantly (2 Thess. 1:3). He also exhorted the Colossian believers to walk in Christ and be rooted, built up, and established in the faith (Col. 2:6–7). Our spiritual fitness increases as we walk in Christ—in faith, looking to him, resting in his perfection, and seeking to know him more.

3. To Build Spiritual Fitness, Keep at It

Faith only grows when it is exercised. If we rarely use this spiritual muscle, it will initially feel very weak. Someone who’s never done a push-up before can’t drop down and give you 50. They’ll barely be able to do five.

Why do most people struggle to grow physical muscles? Because it’s painful. It takes a lot of work and constant practice. It can be unpleasant if you’ve never done it before.

Spiritual fitness can feel like that, too. But just like physical training, the more you exercise the spiritual muscle of faith, you’ll not only come to see that you’re gaining strength, but that it’s a lifestyle of great blessing and even enjoyment.

Don’t wait until a crisis to exercise this muscle. Start small and begin walking by faith more and more each day. Here are a few ways you might do this:

• Just as protein fuels muscle gain, you need a steady diet of God’s Word to grow in faith.
• Pray through Scripture and ask God to give you the grace to apply it in some way throughout your day.
• Make it a practice of praying before seemingly insignificant moments. Pray every time you get into your car that God will bring you safely to your destination. Pray before every meeting you have at work. Pray before you walk into your house for your interactions with family or roommates.
• Start your day praying through Proverbs 3:5–6, asking God to be ever-present in your heart and mind.
• End each day by giving thanks for how God has blessed you and crying out to him for the things that remain unresolved or painful.

4. To Build Spiritual Fitness, Nourish Your Soul

What you do outside the gym is just as important as what you do inside. No amount of time on the treadmill will undo the harm of eating three donuts every day for breakfast. The same is true for our spiritual fitness. We must be on guard with what we’re feeding ourselves spiritually. Even if we’re steady in a daily routine of Bible reading and prayer, we can still find ourselves in great spiritual weakness if we’re daily filling our minds with the things of this world. The author of Hebrews exhorts us to “lay aside every weight, and sin which clings so closely, and let us run with endurance the race that is set before us . . .” (Heb. 12:1).

Jesus alone can do this work because he alone was the perfect man of faith, able to endure the cross for the joy that was set before him.

This takes prayerful discernment to know what that might mean for you personally. Many encumbrances to the race of faith may not be inherently sinful things, and yet they are weighing us down. From our constant phone use to nightly streaming services to never-ending podcasts, there are an increasing number of ways we can find ourselves trapped in spiritual malaise. Both physical and spiritual junk food are highly addictive. Expect the pullback to be painful, but the gain you will experience is certainly worth it.

5. To Build Spiritual Fitness, Stay Plugged in to Your Power Source

All these tips find their source and destination in Jesus Christ. He is our strength and our food! Apart from him, we can do nothing (John 15:5). In the spiritual race of life, we are not only to throw off every weight and sin, but we are also to look “to Jesus, the founder and perfector of our faith, who for the joy that was set before him endured the cross, despising the shame, and is seated at the right hand of the throne of God” (Heb. 12:2).

Notice that it is Jesus who starts and perfects our faith. Spiritual fitness is all his work of grace in our lives! To put it another way, “he who began a good work in you will bring it to completion at the day of Jesus Christ” (Phil. 1:6).

Jesus alone can do this work because he alone was the perfect man of faith, able to endure the cross for the joy that was set before him. He saw with eyes of faith what was on the other side of the cross. He knew by faith that he would rise from the dead, ascend into heaven, and bring all his redeemed people home with him.

Are you in a place of spiritual weakness as you read this? Look to Jesus. Do you feel unable to face the pressures of life on your own? Look to Jesus.

Your flesh and your heart may fail, but Jesus is and will be the strength of your heart and your portion forever (Psalm 73:26).