We all feel we are non-judgmental. The reality is it is very difficult to be without judgment.
We all have our biases and prejudices. The only way to be aware of our biases is to catch ourselves in the act.
For instance, when you find a colleague always takes long to order his/her food, and in your mind you think, ‘there he or she goes again’ OR if you are in a line up and someone takes longer to conclude a purchase, and you say, ‘how long does it take to make a simple transaction for God’s sake?’ These are but a couple examples of judgemental remarks.
Not everyone can be like you. Just because people are different from you does not make them objects for judgment.
Accepting people the way they are, not the way you want them to be is the foundation of being non-judgemental. Not so easy!