Here is motivation to share the Gospel with others! But a caution is in order here. The Bible does not contradict itself, so what are we to make of this verse in comparison to these below that show that God is the one who chooses people and saves people, when this verse in James makes it sound like we are able to convert people?
Ye have not chosen me, but I have chosen you, and ordained you, that ye should go and bring forth fruit, and that your fruit should remain: that whatsoever ye shall ask of the Father in my name, he may give it you. -John 15:16
But we are bound to give thanks alway to God for you, brethren beloved of the Lord, because God hath from the beginning chosen you to salvation through sanctification of the Spirit and belief of the truth: -2 Thessalonians 2:13
But as many as received him, to them gave he power to become the sons of God, even to them that believe on his name: -John 1:12Which were born, not of blood, nor of the will of the flesh, nor of the will of man, but of God. -John 1:13
Given the whole of Scripture, I have to say that what this verse is driving at is that we are the means for taking the truth to others. God uses means and we are supposed to tell others about Him and about His truth. It is the truth of God's word that changes people. God is the one who does the converting, but we have a part in it by participating and obeying God by telling others the Gospel.
I was once a member of a church that had this messed up. They apparently believed they were the ones doing the converting of men's souls. Every Thursday evening they went out "soul winning". Now I admire their zeal, but their method was deplorable. They would knock on a door and proceed to lay out the Gospel to whoever answered the door if they were polite enough to not send them packing. Rather than allow God to work in the person's heart in His timing, they would stay on the doorstep and press the person to make a decision for Christ right then and there, refusing to leave until the person had prayed the sinner's prayer with them.
I watched in horror week after week as they hammered people over the head with the Gospel 2 x 4, refusing to leave the doorstep until the sinner's prayer was prayed. Each Sunday they added the numbers of souls that were saved to a banner up front. I found it sad that for all the numbers of souls they claimed to save each week only two of them showed up to church and they didn't keep coming. It was apparent to me that they thought they were the ones "saving souls".
We need to be sure that when we share the Gospel, we remember that God is the one who saves. Our job is to plant the seeds and water it. God's job is to give the increase.