Being easily distractible means you frequently forget your own plans and make hilarious (and sometimes dangerous) flipflops. And your decision-making can suffer
I don't flip flop so much, but I do have a tendency to put off decisions and also make impulsive and poorly thought out decisions.
There may be two different topics; indecision in general, and being indecisive when feeling a loss of control.
I used to be affected by the latter as well, and I came to the conclusion that I need to be assertive. The lack of assertiveness and being a 'nice guy' made me frustrated due to the feeling of lack of control. Once, I established that there were parts of control that I was willing to give away and embrace the concept of surrendering, my life became low stress.
For example, I would have done the opposite of you with the cafe example. I would have texted yes and regretted it all the time because I would have believed that I was put in a spot. Instead, by being assertive, and responding with "Actually, I would have loved to, but I need some "me-time" helped me regain control. The upside of assertiveness is that I could also often surrender with the rationalization that "hey, someone else making a plan on my behalf is terrific, and the fact that they want me to be present with them is a privilege," and that made my mood undoubtedly better when I did indeed join them. So, instead of getting a grouchy dad at the cafe, they would have seen a smiling me enjoying myself.
This book from a Stanford Univ couple Sharon and Gordon Bower helped me a lot https://www.amazon.com/Asserting-Yourself-Updated-Practical-Positive-Change/dp/0738209716
Gordon Bower won the National Medal of Science.
See the DESC script from the above book: https://your.yale.edu/sites/default/files/adviformanagers_usingdesctomakeyourdifficultconversations.pdf
Re Nice Guy - this book is very interesting https://www.amazon.com/No-More-Mr-Nice-Guy/dp/0762415339
Book summary on youtube: https://youtu.be/hz-Uo4iMvn4
Hard relate for me. Thanks for writing on this!
This sounds terribly like the things that happen with me. For instance today I made at least five flip flops around going out in the evening. This happens all the time. Another frustrating aspect is that when there's many distractable elements at work, my statelessness is a disaster. For instance, I may be putting together a presentation and need to refer to a thread in Slack but the moment I get there, other things in slack suck me in and soon it's fifteen minutes later and I've forgotten that I was originally working on a presentation at all. It's insane.