Ahimsa is the first of the Yamas, as taught by the Ancient Sage Patanjali in his text, the Yoga Sutras.
Yama means restraint or control, and the five Yamas in Yoga essentially represent ways that we should try to behave towards others. However charity begins at home, and these five guidelines for our conduct should be applicable to ourselves first, so that we can then practice them within our families and communities.
Ahimsa is usually translated as "non-violence", and as such, can encompass a variety of behaviours, including compassion, generosity, peace and tranquility and of course love; the latter of which means showing ourselves love in both our practice and our lives.
Here's what the Bhagavad Gita says about Ahimsa:
"Do not get angry or harm any living creature, but be compassionate and gentle; show good will to all. Cultivate vigour, patience, will, purity; avoid malice and pride. Then, Arjuna, you will achieve your divine destiny."
So how do we practice Ahimsa? Primarily, we are looking at how we treat ourselves in our practice; so, for instance, are we forcing our bodies to do too much? Pushing a little too far beyond the "stretch" edge and maybe into pain? Keeping a weather eye on what we're feeling as we work is key, and we should always stay within our "intelligent edge". Some sensation is of course required, or there wouldn't be any point practicing - but not to a level that might risk or cause injury. There's not much room on a yoga mat, so try not let your ego try to push you off it!
Similarly, are we pushing too hard in other areas of our lives? Are we, for instance, allowing our career or our addiction to email and social media affect our work-life balance, or our relationships with our loved ones? Are we practicing ahimsa towards other beings, maybe by thinking more about where the food we eat comes from, and whether animals have been made to suffer in its production? What measures can we take to reduce our enagement with factory farming, or to do more to protect the beauty and splendour of our home planet?
Yoga is about learning to understand ourselves, recognising our needs and limitations. Self-care is not an indulgence, but rather a pre-requisite and starting point to keeping us nourished and fulfilled, so that we can be the best version of ourselves; then we can go out into the world and take care of others. Ahimsa asks us to investigate where we may be causing ourselves pain or distress by pushing beyond those limits, and in so doing, potentially causing harm to others, in thought, deed or action.
Work towards being more kind, accepting, and forgiving to yourself and others, by first practicing these qualities on your yoga mat.