"Once I finish this project, I will start living properly."
The list does not end. The degree, then the job, then the move, then something else that is not even visible yet. The condition stays one step ahead, because it moves with you.
This is not about planning. Planning is fine, and so is postponing specific things for specific goals. The difference is what exactly is being postponed. Not a trip and not a purchase, but the status of what is happening: the present is declared a draft, now does not count, counting starts later.
There is a cost here that rarely gets counted. Drafts are not remembered. Five years on, almost nothing is left of a postponed period — not because nothing happened in it, but because you did not mark it as life and did not keep it.
Later is also now, just a different one. And you will arrive there with the same habit: the habit is not tied to circumstances, it is tied to how you treat the current day.
One question tests it. Remove the condition: what changes today? If nothing, the condition was never about living. It was about permission to start.
You issue that permission. No project issues it for you, a thesis defence included.