This is a hallmark of traditional daoism: wu-wei, or (as it is often translated as) non-acting.
It simply means that you should not think about what you do or say. If you simply exist as the being you are, you will have little worries.
No intention also means: to let go of your desires, your plans, your wishes, your dreams, your future and your past. No expectations and no remorse. It is how it is.
However, as we are human beings, we are born with desires, dreams and a linear sense of time. Our identity is linked to our past and our future. Moreso, our brain is a machine geared to predictions and probabilities. So for us humans, it will be impossible to achieve a completely free state of wu-wei.
This, of course, does not matter. It is how it is. We cannot deny our human nature, and we don't need to.
Self-confidence is the basic premise for wu-wei. As a human being, you are stuffed with qualities due to nature and nurture. We see, hear and smell; we sleep, eat and dream. Love (or compassion) is an important part of our toolbox. It is easy to act without intention, if you realize that all your deeds and words arise from the pool of love that is inside you.
And even if this is not the case, whenever you hurt or insult someone else, whenever you bring harm to this world, even then you are still who you are and therefore you have not done something wrong. Moreover, there is no wrong or right in the dao.
So to act non-intentionally, you simply have to live. Be whoever you are, say whatever you want to say, do whatever you want to do. Be confident in yourself, you are a creature of love, and there is no right or wrong.
If you follow this simple guideline, your life may become lighter, free of worries and regrets, and as you give your love to other people, you will very likely receive it back. It is like a smile.
For example: life is change. Do not force the change, do not act with the intention to change. If you act non-intentionally, change will be present anyway.