Zen Buddhists believe in something that the West calls "living in the moment," or, in other words, "going with the flow." This means that Zen Buddhists, and certainly other Eastern traditions, don't spend nearly as much time being stuck in the past or worrying about the future in the same way that many of those outside of these traditions do. "Living in the moment," requires living life without judgement.
When we think of living life without judgement, or "being less judgmental," we usually reflect on how we think about other people and the negative thoughts we formulate in our heads without truly knowing someone else, thoughts such as, "She's really bossy," or, "He's very arrogant." While this is certainly apart of living life without judgement, it certainly does not encompass the entirety of its practice. In fact, living without judgement also involves the thoughts we formulate about ourselves, our relationships, our habits, and, well, everything within our lives.
When people think about Zen Buddhists or others who practice these philosophies, they usually picture monks meditating in a mountain somewhere, eating only rice and drinking water for survival and not truly taking pleasure in anything. Maybe there is a small grain of truth in this, but the truth is that anyone can practice living life without judgement. You certainly do not have to practice asceticism to do this.
Asceticism is a spiritual and religious practice devoted to strictly avoiding all forms of indulgence. However, many great spiritual leaders will tell you that asceticism does more harm than good. In fact, even Siddhartha Guatama, the original Buddha, needed to be nursed back to health after nearly starving himself to death. When he was well again, the Buddha realized that all things in life simply require balance to avoid doing harm.
In other words, if you wish to properly "live in the moment," and live life without judgement, you don't need to avoid indulging in your favorite activities such as eating ice cream. In fact, a good Buddhist will probably to tell you to eat the ice cream, and enjoy doing it! You simply shouldn't eat more than what it takes to make you full, and you should enjoy the ice cream for what it is. You shouldn't be thinking about also eating cookies while eating ice cream- this creates a longing from something else while you're supposed to be enjoying what you already have.
Maybe eating ice cream is a silly example to describe, "living in the moment," but what about the bigger things in life, like your relationships with others? This is where living without judgement is key! Before complaining about those around you, like the parent or the spouse that nags you all the time, the sibling who is "annoying," because they want to spend time with you, or the friend who gives too much advice because they want to see you do better, what about subtracting the negative observations of all of these relationships and placing them with positives?
What about enjoying these people for what they are instead of what they could be? Your parent or spouse nags because they want you to be productive. Your sibling wants to spend time with you because they enjoy your company. Your friend gives you advice because they want to see you thrive.
Living without judgement AND living in the moment are all about enjoying what is immediately around you and being gracious for it! Philosophies like this are only meant to help you and your life. It isn't always easy to change your way of thinking, and sometimes, it can seem impossible! But start simply. Sit on your front porch with a book or a cup of tea. Look around you. What do you see and enjoy? Don't worry about the cars or the construction going on up the road. What about the birds chirping, the flowers blooming, and the sun shining? Just be grateful. Or otherwise, just be.