The third thing you will need to help you train for godliness is an education. Remember that while what Paul said in I tim 4:7 was in a context of physical training at a gymnasium, he was making a spiritual application. If you want to train for a physical event such as a marathon, you soon realize that having the desire to run a marathon and the goal for running it (e.g. to finish or beat your last effort) must be followed up by learning what you need to know in order to training for that race.
Let’s say you decided that your goal for being godly is to get to Heaven. (In other words, you would rather live than die!) Now what? How do you know if you are training correctly or not? How do you know if you are progressing toward godliness or moving further from it? You will need knowledge. God’s word tells Christians:
So put away all malice and all deceit and hypocrisy and envy and all slander. Like newborn infants, long for the pure spiritual milk, that by it you may grow up into salvation– if indeed you have tasted that the Lord is good. (1Pe 2:1-3 ESV)
Just as a newborn baby will feed on milk, so the Christian must feed on God’s word. Remember you when you obeyed the Gospel, becoming a Christian, how you wanted to know everything? The milk was good and helped you grow. Knowledge, in training for a marathon, says ‘put away milkshakes, sugars, and french fries” and, in a spiritual training, you put away ‘malice, deceit, hypocrisy.”
Yet at some point, milk needs to be left behind:
For though by this time you ought to be teachers, you need someone to teach you again the basic principles of the oracles of God. You need milk, not solid food, for everyone who lives on milk is unskilled in the word of righteousness… solid food is for the mature, for those who have their powers of discernment trained by constant practice to distinguish good from evil. (Heb 5:12-14 ESV)
Christians, who should have progressed on to meat in their training, have actually reverted back to a need for milk. Just like an athlete with good training habits who stops those habits will soon find that even a simple 1 mile run is hard, so Christians will find that godliness is hard if they revert back and do not progress.
The Knowledge we need is in God’s word. David spoke often of his delight in the law of the Lord. Below is one passage. Many more exist in Psalms, I would suggest you read Psalm 119 and see what David says about God’s law, precepts, commandments, and ways.
Blessed is the man whom you discipline, O LORD, and whom you teach out of your law, (Psa 94:12 ESV)
Knowledge also comes by example. We learn what to do, or what not to do, by seeing what others have done. The Bible is full of examples of those who serve as models to follow and examples to avoid. What was written before was truly written for our learning. (Romans 15:4)
The knowledge you gain by studying God’s word is both of God’s law and of His character. Truly, a person will be godly when they are like God but until such a time as we actually reach that perfection, we continue to exercise ourselves toward godliness learning from the knowledge He has given us about Himself.
as His divine power has given to us all things that pertain to life and godliness, through the knowledge of Him who called us by glory and virtue, (2Pe 1:3 NKJV)