How many of the thoughts you are having right now, or in any other moment, actually contribute to what you are doing and experiencing? When you examine this, you will discover that most thoughts don't contribute to your life, and they aren't needed to function. Try to find an example of a thought that is necessary. Necessary thoughts are few and far between.
Isn't it funny how important and necessary we think thinking is? This is part of the grand illusion. We think we need to think to make life happen and make it go smoothly. But when we examine the contribution our thoughts make to each moment, to our experience and to whatever we are doing, we discover that not only are thoughts unnecessary, but they clutter the moment with confusion, negativity, and stress and so interfere with what we are experiencing and doing—and with our happiness. Our thoughts interfere with our happiness because they are so often demanding, pushy, or judgmental (e.g., “You have to get this done now!”). Such thoughts cause stress that can easily make us feel overwhelmed by life.
Life is never actually overwhelming because there's only so much we can do in a moment. But the mind brings ideas into the present moment about what we “have” to do, what we want to do or can do, what we've done, what others want us to do, and about any number of things unrelated to what we are doing or need to do. Such thoughts confuse and stress us out. They are not only unnecessary, but counterproductive. Stress makes us less effective and efficient, crabby and unhappy—and it's unhealthy. Those are the real results of giving our attention to thoughts and letting them guide our life.
The good news is that nearly all of our thoughts are unnecessary, not just a few of them. That makes discriminating between them much easier. You don't have to go sorting through your thoughts for the right ones. You just need to recognize that egoic thought belongs to the false self and is therefore false and not worthy of your attention. You can disregard all the thoughts that relate to me and my life and all the other chatter, judgments, opinions, memories, fantasies, dreams, desires, likes, dislikes, doubts, fears, complaints, and other negativity of the ego.
What you are left with is a functional mind that still knows how to read, calculate, use a computer, drive a car, follow a map or instructions, and do all the other things that the mind was designed for. The functional mind is something we use when we need it; it doesn't talk to us like the egoic mind. What a relief it is to realize that the voice in our head can be ignored! Can you trust this? Just start noticing how you don't need any of your thoughts to experience the present moment and to do what you need to do. See for yourself.