Developing a strong human spirit requires developing your spirit-man to be in tune with the Holy Spirit. You will never learn how to follow that still small voice without training your spirit-man to listen to Him. We grow in God by reason of use, by using our spiritual muscles (Hebrews 5:14). If it is so important that we train our spirit-man, how do we do that? We exercise, and the greatest exercise is to discipline ourselves to regularly read the Word of God. 

There is no way to grow in the things of the Spirit outside of having a working knowledge of the Scriptures. You must read your Bible daily, and meditate on what you read. As your inner man is in training, quality is more important than quantity. It is better that you meditate on a few scriptures than it is to try and read 10 chapters of the Bible at a time.

To meditate means to take something into the depths of your thought processes with such esteem that nothing contrary to that will have a place in your thought life. It means to get quiet enough when you read the Word of God to allow the Holy Spirit to explain to you what you just read.