Compassion for yourself and others is the key to a long life

Yes. It is also true that diet, the people you hang out with, your basic common sense and other factors are important to. But, if you have all the above including good genetics your chance for a long and healthy and happy life are the highest when you have compassion for yourself and all others.

You might say, "How do I develop compassion for self and others?"

The primary key is starting with yourself. If you hate yourself and want to kill yourself then you could also easily if you are not careful accidentally or on purpose kill others too.

So, learning how to have compassion for yourself will not only save your life it will save other lives as well.

How does one develop compassion. In Tibetan Buddhism people are taught to see all living beings as once having been their mothers. (Even if you don't believe this is true try this as an exercise the next time you look at a deer, or dog or person or even an ant or fly. Think of this being in one lifetime having once been your mother and birthing you and taking care of you. You owe this being a lot for the sacrifice this being gave to you as your mother in that lifetime.

This is the Tibetan way of developing compassion for others and in the process you will find yourself developing compassion also for yourself because you are showing compassion for your mother in whatever form she now appears to you.

So, whether you believe all this is true or not you have learned one way to begin to develop compassion for yourself and all beings.

Another way I like is the following Buddhist Prayer:

"May all beings attain bliss and the cause of bliss
May all beings be free from suffering and the cause of suffering
May all beings never be without the Supreme Bliss that is free
from all near and far all grasping and aversion."

This I experience as being true for all living things in the universe right now. By doing this it brings me great happiness and joy. By experiencing this it speeds up this actually happening for more and more beings every moment of every day until one day all beings will live in supreme bliss and be permanently free from all suffering forever.

Since both Time and space are only relatively real and being and non-being are the only true reality
life is but a moment in time that never ends. And in this eternal moment all beings are free from suffering and all beings live in eternal bliss.

And this is Grace and eternal peace.