Zen master Thich Nhat Hanh expresses it simply, saying that whenever he drinks a glass of water, he invests himself 100% in the drinking. He then encourages us to do the same with everything we do.
This sounds simple enough, but the practice can be quite challenging. Still every step in that direction is liberating. In fact, in Buddhist teaching, this simple practice can make us liberated beings, entirely free from delusion and sorrow.
We should not underestimate the power of mindfulness.