It seems that he means it.
God, if he is indeed God, cannot change, cannot lie - and, I'd be willing to bet, he doesn't even exaggerate. Well, I suppose that the Lord did, a bit, or used exaggerated language in order to get across some very serious points, but, in himself, I don't think he does.
So when he says he calls...he calls.
If the saints tell us that he chooses people, they mean real people, people who have a certain height, a certain hair color, noses and hands and fingers of a certain shape. People who like pizza - or don't. People who have amazing talents ... and equally amazing blind spots. In short, if God says he calls people, he calls people - real, live, flesh and blood people... like me, like you.
And we sort of cringe at that. "I'm not worthy." Check. "I've done stupid or sinful - in a really big way." Check. "I'm not holy enough." Check. "Who, ME?!?!?!" Check.
It's not about us. It's about him. He loves. You. Me. His Church. All the people of the world. He looks at individuals, real people, and just loves. And so he calls. We're NOT worthy, but that love loves us into worthiness, not because of any gifts or talents we already have, but out of the extreme prodigality of his gifts. Love makes worthy the beloved.
So, don't be afraid or balk or worry. Because yes, he is calling you to some great thing. What it is - well, figuring that out is discernment. The call is there, go for the gold.