Busting your ass planning something important? Feel like you can’t proceed until you have a bulletproof plan in place? Replace “plan” with “guess” and take it easy. That’s all plans really are anyway: guesses.
As my old boss used to say, plan the work and work the plan.
But I take the same approach to planning as I do for traveling: set up the ground rules and structure, and then let real life interject – as it always does.