Why can I plan something but never finish it?

You already made the plan. That part was never the problem. The trouble starts when you look at the whole thing at once — every step, every meeting, every unfinished piece — and your mind calls that one giant task. No wonder you freeze. No one can carry a mountain in one trip. This is not a flaw in your character. It is a trick of attention. The plan lives in your head as a single huge object. But it was never meant to be done all at once. It was only ever meant to be done one piece at a time. You have no power over the whole project finishing. You never did. You only have power over the next action in front of you. Stop reaching for control you were never given, and take the control you actually have.