When I think about my young dreams to play professional sports, they were perhaps not dreamt in accordance with my talents. They were aspirations, but not aligned with reality. I didn't pay enough attention to what I was actually good at and think about my dreams related to my actual skills. I just liked playing basketball. It's a shame I was terrible at it.
Paul, here, is called to be an apostle. It's interesting to think about Paul's life -- while he was trained and skilled in religion, he certainly wasn't trending towards Christianity as he was persecuting it. But God called him -- he had leadership skills and plenty of passion. He needed a little adjusting, but God took care of that on the road to Damascus!
Others were called to be saints together. They weren't called to be apostles -- they had other calls, just as important, but different. We're not all called to be apostles.
So when you listen to how God is calling you, pay attention to what is going on in your life around you, to the skills and passions that you have, to the community you have and how they affirm you in your life, and then move in that direction, listening for God's Word to continue to guide you, often speaking through those around you. It can be hard to find your call, but we're all called -- some as apostles, some as saints together, others in other roles. Thank God we have one another!