Dedicated to the Lord Jesus Christ Who loved us, gave Himself for us, and washed us from our sins in His own Blood; and to the Church, which is His body.

The second type of person Jesus describes is one who does receive the Word, even with great joy, but his commitment to the Word is shallow. Just like a plant must establish a strong root system to sustain its growth, we must become rooted and grounded in God's Word. Too much attention on visible growth will cause us to become impatient and not take the time to become firmly established in God's Word. This will cause fruitlessness.
A seed planted in shallow earth will germinate and grow faster than a seed planted in deep soil. The seed in deep soil will put all of its energy towards the roots first while the seed in shallow soil has no choice but to put its effort into the growth of the plant above the ground. The plant in shallow soil will look like it is far ahead of the other seed for a while, but that will not last. It soon withers and dies, while the seed with roots grows and brings forth fruit.
Afflictions, persecutions, and tribulations are instruments of the devil and are used to stop God's Word from bearing fruit in our lives. They are not good things that God brings our way to improve us. They are instruments of Satan. These things are to take our attention off of God's Word, stopping the Word from taking root in us. 
It's like the runner who spends all of his time in the grandstands arguing with the hecklers over the way he's running the race. He may win an argument, but he will lose the race. We must not let anything distract us from meditating on God's Word day and night, only then will we make our way prosperous and have good success (Joshua 1:8). 
By consistently putting God's Word in first place in every area of our life, will we let that Word become so rooted in us that nothing can get it out.