A Sower went out to sow. And as he sowed, some seeds fell along the path, and the birds came and devoured them. Other seeds fell on rocky ground, where they did not have much soil, and immediately they sprang up, since they had no depth of soil, but when the sun rose, they were scorched. And since they had no root, they withered away. Other seeds fell among thorns, and the thorns grew up and choked them. Other seeds fell on good soil and produced grain, some a hundredfold, some sixty, some thirty. He who has ears, let him hear.
Matthew 13:3-9 (ESV)
The parable of the Sower was the first parable that Jesus used to illustrate life in the Kingdom. It is not addressing salvation, but rather the condition of one's "spiritual soil" or heart. Each soil stands for one of the four ways a believer could respond to the message of the kingdom. Success or failure does not depend on the skill of the Sower of the good news. The problem is not the seed (which represents the word of God). It is the soil that determines the varying degrees of fruitfulness or barrenness.
Jesus said that we would go through a lot of trials and tribulations that would tempt us to compromise our spiritual growth. And the devil will take advantage of the circumstance to cast doubt on God's word and goodness. If you leave your heart unhealed and untended, it will follow its natural predisposition and grow hardened to the truth. Once doubt and unbelief set in, they will keep you from remaining faithful and fruitful.
Only God can change the condition of our heart.
In biblical terms, the heart refers to our spiritual orientation, whether it is inclined towards God or something else. In other words, the spiritual state of your heart will influence how you respond to and follow Jesus.
Instead of getting disheartened or defeated by life’s unavoidable disappointments, pray for God to quicken you by His Spirit so that your heart stays “abide” in Jesus. Be a good soil. Allow Jesus to fill your heart with His life so that you can continue to enjoy the blessings and benefits of His love, grace, and truth.