From Chapter 3 of Fully Present, some thoughts on not being so judgmental and instead just letting things be:
... One of the main tenets of mindfulness practice is to be aware of things exactly as they occur. We learn not to try to control our experience in life, but to let it unfold, exactly as it is. This cultivates a quality of calm acceptance of life—although we do not necessarily become passive! ... We gain skill in observation and acceptance rather than control.
A few pages later the authors, Susan Smalley and Diana Winston, discuss the need for practice and patience, reminiscent of how to learn to juggle ("drop by drop", as the saying goes):
In the beginning it may feel like you are aware of one breath but soon are lost in thought; after a while you return to your breath, but before you know it you are thinking all sorts of thoughts; you go back to your breath ... and so on. This is a completely normal meditation session! Following your breath is a practice. No one does it perfectly from the start. You simply need to keep coming back again and again. This is where the learning occurs, and ultimately you can train your mind to return more frequently and for longer periods of time. Try to be kind to yourself. Don't yell at yourself in your mind. (Get back to the breath!) You are learning a new skill that may take time; getting angry or frustrated at yourself will not make you more skilled; in fact, it will probably make you feel worse.
Think of it this way: If you want to build muscle, you need some resistance. That is why you work out with weights. Imagine how ridiculous it would be to try to build muscles by lifting a pencil. In meditation, our minds are working out too, trying to build a new brain pattern, something like a mindfulness "muscle." Resistance helps develop strength. The wandering, fantasizing, thinking mind is the resistance, and a very high-quality resistance at that. The more you train yourself to return your attention to the present moment, to your breath, the "stronger" and more skilled you will become at doing so. ...