There are two primary motivations for making disciples.
The first is that Jesus commanded us to do it. Matthew’s version of the Great Commission (Mt 28:18-20) commands His disciples to make disciples. Our love for Jesus motivates us to do what He has commissioned us to do. To explore this more, you might want to consider the mission of the church.
Secondly, there are numerous benefits from making disciples.
May God Himself motivate you.
Why Make Disciples? – article, Jonathan Dodson