When my daughter was within a few days of being born, it finally dawned on me that I was the person who would be the dad. Sounds silly I know. But, I wasn't going to improve dramatically, or mature in the next few days and become an adult super-dad. I'm it, this is what a dad looks like.
I think it's the same for everybody. God calls us to our various vocations and that's it. God doesn't what us to improve ourselves then follow. God wants us to simply follow.
When Jesus called the first disciples he said "Follow me." And they did, they literally dropped what they were doing and followed. Imagine if Jesus said "Follow me, but after you've lost that spare tire, and sussed out your theology, and clean the kichen too." I think I actually would prefer that, because then I'd never have to actually get around to seeing what God wants me to be doing.
You're it, we're it, God bless us, we're not going to change all that much on our own.