What everyone said! It takes time.
Slowly you have more days where you are the parent that you want to be than days you don't. But start small - with small changes and don't beat yourself up when you resort to yelling (even though I still did!)
Even now Im probably still not always the parent I want to be every moment and thats with years here, reading, changing, reading books recommended to me, etc. etc. But I keep working at it.
I would get stuck on what to do - ie could only think of something punitive, so like you, would do nothing. But I would post my specific situation here and get great advice and slowly it became more natural (though I still need advice and help at times).
I hope you stick around and I hope we hear back from you soon!