Begrudging God's Generosity

Currently, I'm reading through Matthew in my quiet times. And how many times have I heard this parable - yet the faithfulness of the Spirit is quick to teach me new things from the Word.
Matthew 20 is the story of the laborers in the vineyard. Where the master hires workers at different times during the day, but each one getting the same wage. Here is the end response of the master after being questions by the workers who started at the beginning of the day:
"Friend, I am doing you no wrong. Did you not agree with me for a denarius? Take what belongs to you and go. I choose to give to this last worker as I give to you. Am I not allowed to do what I choose with what belongs to me? Or do you begrudge my generosity?"
I often do this - ok, no I don't want a denarius for working in the field all day. Here is how this applies to me.
I often wonder why I am not actively involved in a paid ministry position at some church - I have a seminary degree?
Why aren't I married? Other people are.
Why don't I...
The list goes on and on....
How I begrudge the generosity of God just a bit (at first) when I hear of friends who get pregnant or get a ministry job or are planning their wedding.
Why? I was created in God's image and what did I do with it - spat on it. Turned away from it.
And yet...God's generosity gave me His Son (Rom 2.4). Out of His Supreme Plan He chose me. Yet - I mock His generosity?
How do you begrudge the generosity of God?