Plans impress minds; completion changes circumstances.

A plan is persuasive to people, including you, because it lives entirely in a world where everything goes as described. Completion is the only thing that acts on the actual world, and its effects are unaffected by how impressive the plan sounded. The two operate in different domains.

Notice if you are getting your satisfaction from the planning. Move the satisfaction to the delivery instead, by keeping the plan short and starting the work earlier than feels comfortable.