No. You do not need to stop thinking in order to meditate.

A little experience will reveal that stopping thought by an act of will is extremely difficult. Try it! Try to stop thinking. How long did you manage? Five minutes? Five seconds? Less?

So should we simply let the mind wander wherever it wants? Not quite.

Thoughts are strengthened when we continually attend to and follow them. A thought arises, we follow it, and before long one thought has given rise to ten thousand others. In Zazen, therefore, we give our attention to the object of meditation—the out-breath and, initially, the count.

As soon as awareness arises that we have been carried away by a stream of thought, the practice is simply to let go of it and return to the object of meditation.

So remember: if it is fed, it grows. If it is not fed, it gradually loses its hold.