In order for you to be kind to others you must start by being kind to yourself.
How many times in a day are you self-critical?
Pay attention to this and when you find yourself being unkind to yourself, stop and apologize to yourself.
This in itself is a kindness and then be kind to yourself.
Pay attention to how your children and grandchild treat themselves
and when they make unkind comments,
gently redirect them and teach them about self directed kindness,
so they in turn can be kind to others.