I have written to you, young men, because you are strong, and the word of God abides in you, and you have overcome the wicked one.
1 John 2:14
There is no end to the many ways of becoming strong: food, supplements, workouts, personal trainers, discipline in training. What you won't find in advertisements for gaining strength is a recommendation for memorizing and meditating on the Word of God. Scripture won't necessarily make you physically stronger, but it will make you stronger in the most important of ways: spiritually.
Recommended Reading:
Ephesians 6: 10
The greatest challenge we face is overcoming "the wicked one." Satan not only puts obstacles in our path to believing in Christ, he puts temptations in our path to keep us from following Christ. And that is where the Word of God comes in. Because Satan uses lies and counterfeits as his chief weapons, the "word of truth" (2 Corinthians 6:7) gives us victory over him. Just as Christ defeated Satan's temptations in the wilderness with the Word of God (Matthew 4:1-11), so can we. But only if the Word of God "abides in you."
For the Word to abide in us, we must put it there by reading, meditating, memorizing, and studying it. That's how we become spiritually strong.
Holiness is not freedom from temptation, but power to overcome temptation.
G. Campbell Morgan