“I preach the gospel … I am under orders to do so”. 

1 Cor 9:16 GNB 

Most people do their work in order to earn money with which to feed themselves. Others do the particular work they are engaged in because they have a specific talent for it and it gives them an opportunity to express themselves – as well as giving them an income. 
Paul was a full-time apostle. He went round from one town or city to another in order to preach the gospel, call believers to repent, and to teach and build up the resultant community. He was also a tent-maker by trade and sometimes paid for his keep by turning his hand at his trade. But he did not go around preaching in order to make a packet. He did it because he was under orders – God’s orders. He did not sit around and work out what was a good occupation. God came to him out of the blue and gave him his orders. Preaching is the fulfilment of a calling – from God. You do not choose it – God chooses you. You merely obey. That is why Paul was where he was. 
He could do no other. Had he not responded to the call he would have regretted it all his life long. But he obeyed the divine call and he changed the church – and history – for all time. 
If God commands you to undertake a certain kind of work, make sure you respond positively. God does not confine his calling activity exclusively to religious vocations. He calls some to teach in schools, others to nurse in hospitals, yet others to build houses, manage businesses, wield power in politics and build up the community. 
Have you responded to his call? 

Lord, thank you for your call to your servants..