Spiritually fit

I was reading Hebrews 5:11-14 today.  "About this I have much to say, and it is hard to explain, since you have become dull of hearing.  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, since he is a child.  But solid food is for the mature, for those who have their powers of discernment trained by constant practice to distinguish good from evil."

This part that made me think and pray today is this idea of being "trained by constant practice."  Now, something I notice a lot on facebook and particularly on pinterest are new ideas for how to become more trained, more physically fit.  There is so much to find about how to tighten your post pregnancy belly, 10 minutes to awesome abs, la la la....and of course I would love to have a super model bod as much as the next girl but let's be honest, it's probably never going to happen and I may never even lose 10 pounds but what I care more about and is that I am SPIRITUALLY fit.  (of course they are not mutually exclusive.)  I wish I got more encouragment though to be spiritually fit...to be trained by constant practice to discern good from evil.  So of course I went to my favorite, John Piper to see what he had to say and I could never say it better:

"Now this is amazing. Don't miss it. It could save you years of wasted living. What verse 14 is saying is that if you want to become mature and understand the more solid teachings of the Word, then the rich, nutritional, precious milk of God's gospel promises must transform your moral senses—your spiritual mind—so that you can discern between good and evil. Or let me put it another way. Getting ready to feast on all God's Word is not first an intellectual challenge; it is first a moral challenge. If you want to eat the solid food of the Word, you must exercise your spiritual senses so as to develop a mind that discerns between good and evil.
The startling truth is that, if you stumble over Melchizedek, it may be because you watch questionable TV programs. If you stumble over the doctrine of election, it may be because you still use some shady business practices. If you stumble over the God-centered work of Christ in the cross, it may be because you love money and spend too much and give too little. The pathway to maturity and to solid biblical food is not first becoming an intelligent person, but becoming an obedient person. What you do with alcohol and sex and money and leisure and food and computer have more to do with your capacity for solid food than where you go to school or what books you read.

The Way You Drink the Milk

What this means is that if you want to grow up and feast on the fullness of God's revelation, you don't do it by jumping from milk to meat. You do it by the way you drink the milk. The milk has to make you a certain kind of discerning person before you can digest the meat. This is so important because in our highly technological society we are prone to think that education—especially intellectual development—is the key to maturity. This text makes clear that it isn't. There are many Ph.D.'s who choke in their spiritual immaturity on the things of God. And there are many less-educated saints who are deeply mature and can feed with pleasure and profit on the deepest things of God's Word.
So the key to maturity (and the remedy for dullness of hearing) is not jumping from milk to meat. The key is the way you drink the milk—what you do with the milk of the Word. So let me close with three steps in how to grow with milk to maturity.

1. First you drink in the milk. That is, you listen to the milk of the Word—the message of God's promises in the gospel. You read them yourself in the Bible and you sit under the preaching and teaching of God's Word. And you give heed. You are earnest and diligent to apply your heart and mind to what is being said. You are not passive and cavalier and indifferent—babes long for milk, and are incredibly focused when they are thirsty.
2. Savor and swallow and digest and be satisfied. This is crucial. If this doesn't happen, the next stage of discernment will not happen. Here is the miraculous spiritual event of loving what once you hated. You love the taste of the milk: "Taste and see that the Lord is good" (Psalm 34:8). And when the promises of God and the God of the promises are tasted, the milk satisfies. And when it satisfies, it transforms your values and priorities, which leads to Step 3.
3. With a heart satisfied with God now, discern good and evil. There are hundreds of decisions that you must make day in and day out which are not spelled out explicitly in the Bible. What to watch on TV, political positions to take, investment strategies, vocation, insurance, retirement, business tactics, where to live, what to drive, whether to own a gun, how to discipline your children, what to wear, where to volunteer, how much to give, etc., etc.

It doesn't take discernment to know what's wrong if you have a list from God. Knowing when to murder and when to steal and when to commit adultery take no discernment if you believe God gave the Ten Commandments. So verse 14 is talking about decisions that are not laid down specifically in a list.
And it says that there is such a thing as discernment between good and evil. How does this discernment come? It comes from habitually (by regular practice) nourishing and shaping your spiritual senses (the word in verse 14 doesn't mean physical senses) by the Word of God until that word becomes a "word of righteousness"—a discerning power, a word producing righteousness in the mature. Discernment is what you do naturally when the milk of God's promises is so savored and so satisfying that it gives you the mind of Christ."  This is from his sermon "By This Time You Ought to be Teachers..." found at Desiringgod.org.