OP chronic procrastinator here too and, like you, it has cost me dearly over the years.
I’m still trying to deal with it but a few things have has helped me, mainly simplifying tasks. I read “complexity is the enemy of execution” somewhere and it resonated with me. I’m a bit of a perfectionist and over thinker as well.
So, I would procrastinate about going on a ride due to all the faff of getting ready. I now make sure I have all my riding kit accessible before Saturday morning and have the bike in the car Friday night. I go out first thing so it’s just stepping into my gear and then into the car.
Another useful exercise was deliberately only allowing a short time to complete certain tasks eg mowing the lawns usually took me around 45 mins but I would then set a 30 min timer to just get it done. I carried that over to other stuff.
The other thing that helped me was getting my thoughts organised. Sometimes it’s the jumble of stuff you have to get done that is the obstacle.
Good luck and I hope some of that ramble helped.