There are many ways that children can become kind individuals and it can start when they are still very young.
1. Introduce them to people that are different than themselves.
My Late Aunt was in a wheelchair most of her life so I was always used to seeing her like that. But years ago I was babysitting 3 sisters who had never seen anyone in a wheelchair before and they were a little fearful of her. I first explained to them that her legs do not work so she is unable to walk but she is able to move because of the wheelchair. I let them watch her for a few moments before I introduced them. They had no problem with her afterward.
For me, it was strange that these girls were fearful of my Aunt because she was in a wheelchair. But I was happy that I could teach them that my Aunt being in a wheelchair didn't define who she was and although she is in a wheelchair she isn't much different than them.
Children should know that there are people that are other races than them and may be different than them such as those 3 girls who met my Aunt. Young children are very accepting of different people if they see them at a young age. Teach children to be kind to the people that are different than them and to accept people that are different.
2. Teach your child to help others
Have your child Volunteer at food banks, toy drives, bake sales, and animal shelters. Children learn from example, so don't just make them volunteer but volunteer with them. If you like animals call your local animal shelter to see if they can use some more volunteers even if it is just for one day. Most churches run food banks all year long. Ask if they need any volunteers. If they do not, they are always accepting food donations.
Teach your child that volunteers are needed around the year and not only around the holidays. There are many other ways that you and your children can volunteer in your area. Look through local newspapers or talk to neighbors and they may have their own ideas on how you can help your community.
3. Teach your child that we are all equal
It is in human nature to point out differences between us and other people. But we are human and all humans want the same thing. Teach them to treat other people the way they would like to be treated. If you see a moment where your child is being mean to others explain to them how it hurts the other person and how it would feel if someone did it to them.
4. Teach them to be nice to their belongings
Think about a child who mistreats their toys, clothes, furniture etc. This is a child who doesn't respect their belongings. These may be things that were given to them, but the attitude that they don't care about their belongings starts to be reflected throughout other parts of their lives as they start to get older. They realize that there are no repercussions for treating things around them badly and will take that into their lives. They may not treat school or teachers with respect. They may not think tests and grades are important. Teach them at a young age not to treat their belongings poorly. If you have to humanize these objects or explain to them why they should do it for financial reasons that's fine. Such as if they play too rough and the toy breaks they cannot get a new one. Children should not just have respect for people and animals but their belongings, which cost money.
Children should have a level of respect for their elders. Some children seem to have this while others need to be taught it. So if you see your child treating somebody poorly or saying rude things to them correct the behavior. Some people think that they are just young and it's cute and innocent, but it's not. Children who are not taught that this behavior is wrong will not know thart this behavior is unacceptable especially when they are older. As they get older they will think that it is cute and innocent behavior and they will always treat people like that because they do not know that it is wrong.
Find what makes your child happy. Maybe its a favorite stuffed animal, a favorite toy, a TV show, special food etc. Children are more willing to spread kindness and donate their time if they are happy. Maybe your child needs a hobby to make them happy. Maybe it's sports or activity. Let them pursue these things.
Children learn from others around them and that's what makes being a parent so hard. Every action that you do and everything that you say can affect your child and will teach them the right and wrong things to do in life. So if you want a child that is kind you need to be kind yourself. I think that's why kindness seems so rare. Parents are tired, they are busy working and raising children that they don't always have the time or the energy to make sure that their behavior is what they want their children to see. All we can do is our best or maybe just a little more than that.