This verse indicates that heart plans are one thing – thoughts, ideas, attitudes, internal stuff. Words, on the other hand, represent actions, activities, external stuff. Attitudes are on one level, actions (and words) are on another.
People love to make plans. We are full of ideas – some good, some not so good. But we all know from experience – make all the plans we want, it doesn’t make that much difference. As the modern-day wise saying goes, “If you want to make God laugh, tell Him your plans.”
In the end, God has the knowledge, right and power to make happen what He knows is best. We really need to quit making our own plans, quit fighting His plan and simply embrace what He already knows is best for us.