Sounds like untreated ADHD mate. Frequently starting projects and then giving up is a common symptom.
Do you have tonnes of 5% to 15% done projects?
If so, it's because the dopamine hit of (current project) has worn out, and the dopamine hit of (shiny new project) is more enticing.
Do you often burn yourself out early on in the project, your first few days you stay up til 4 in the morning grinding, you progress wicked fast, "this is easy!"
Then suddenly you crash, burnt out, exhausted?
You have to set pace limits on the first days, purposefully stop and take a break.
That rapid fire burn out on week 1 is a big productivity killer, instead literally set the kb+mouse down, get out of the chair and go for a walk. Yes, even though you could keep going, save it for tomorrow.
Try buying an egg timer and force yourself to stop and get up and stretch every hour, and go for a walk after 4 "sets"