The proverb does not condemn plans. “The heart of man plans his way” — that is healthy, even wise: to think, to plan. But the sentence does not stop there.
“…but the Lord establishes his steps.” You draw the route; he adjusts the step. Between the two lies all the room for trust.
“The heart of man plans his way, but the Lord establishes his steps.”
Proverbs 16:9
How often has an unplanned detour turned out to be the true road? We thought we had missed a door; it was he who was opening another.
Make your plans, and keep an open hand. Total control is a tiring illusion; trust, by contrast, rests. Walk with your maps, but let him correct the course.