Constantly thinking about the what if, how do I stop it?

Hi,

Looking for advice/experiences.
I’ve a 4 year old who I find really hard to cope with. In the scheme of things she’s probably not that hard (although I’m suspecting more and more she might have adhd like myself)

I constantly imagine what else I could be doing, how different my life could be. Like how I could be out the house on a morning walking along the beach instead of trying to force a 4 year old to get shoes on to go to the park where she tantrums the whole time anyway.

I know that it isn’t fair and I feel awful.
We so wanted her and tried for a long time and im just not cut out to be a parent, it’s too hard, im too anxious and got overwhelmed too easily, i dont enjoy any of it.

How do I stop doing that? How do i live in the moment more and try to appreciate the little things about having a child?