There was once a pair of acrobats. The teacher was a poor widower and the student was a young girl by the name of Meda. These acrobats performed each day on the streets in order to earn enough to eat.
Their act consisted of the teacher balancing a tall bamboo pole on his head while the little girl climbed slowly to the top. Once to the top, she remained there while the teacher walked along the ground.
Both performers had to maintain complete focus and balance in order to prevent any injury from occurring and to complete the performance. One day, the teacher said to the pupil:
'Listen Meda, I will watch you and you watch me, so that we can help each other maintain concentration and balance and prevent an accident. Then we'll surely earn enough to eat.' But the little girl was wise, she answered, 'Dear master, I think it would be better for each of us to watch ourself. To look after oneself means to look after both of us. That way I am sure we will avoid any accidents and earn enough to eat.'
Explanation: This one isn't a specifically Zen story, but it's said to have been told by the Buddha himself. This story is meant to illustrate that taking care of yourself is the most important thing you can do to take care of others.
By learning how to nourish your mind and body you'll naturally begin to treat those around you with more compassion, love, and kindness and create a more positive impact on the world around you as a whole. There is no division, taking care of yourself (in a spiritual sense, not in a material "buy myself things" kind of sense) equals taking care of others.
Specifically, by taking care of yourself, the Buddha was referring to mindfulness. The Buddha also said that by taking care of others, by showing them compassion and loving-kindness, we take care of ourselves.