Dwight D. Eisenhower, the former president and general who led the successful Allied invasion of Normandy in 1944 once said, “Plans are worthless, but planning is everything.”

I learned the wisdom behind his advice over my years of classroom teaching. I spent a lot of time planning a class session—digesting the reading I had assigned to the students, developing lecture notes and discussion questions that would align with my learning objectives for the course, assembling various kinds of aids to illustrate my points—art, film clips, music, charts, and maps. I did my planning, and I went into class well-prepared.

In my early years of teaching, however, I was often too focused on my plan. I was determined to stick to my plan no matter what. Some days that was ok, but other days it was not. I missed opportunities to dig into a point from the reading or homework that had particularly engaged the students. I missed teachable moments—moments when something happening in the larger world gave me the chance to link the history I was teaching to current events.

With experience, I learned to use my plan as a rough guide rather than a prescription for how the class could go. I did my planning, and because I did my planning, I learned to discern how and when to let go of my plan. My teaching improved as a result.

New parents quickly learn the old proverb that “the best-laid plans of mice and men often go awry,” an adaptation of a line in a Robert Burns poem. Generals know this. So do the coaches of sports teams.

The process of planning readies and focuses the mind, but in the moment, you have to be able to respond to the unexpected. This is true in all aspects of your life whether it’s a project at work, your plans for the weekend, or your career path. Where do you need to loosen your attachment to a plan?

Remember: Don’t feel obliged to stick to a plan, but make sure you do your planning.