From the scientific view, the theory of karma may be a metaphysical assumption -- but it is no more so than the assumption that all of life is material and originated out of pure chance
As an example to others, and not that I care for moderation myself, it has always been my rule never to smoke when asleep, and never to refrain from smoking when awake.
If you let go a little you will have a little happiness. If you let go a lot you will have a lot of happiness. If you let go completely you will be free.
We are what we think, and all that we are rises with our thoughts. With our thoughts we make the world. Speak and act with a pure mind and happiness will follow.
Men are born soft and supple; dead, they are stiff and hard. Plants are born tender and pliant; dead, they are brittle and dry. Thus whoever is stiff and inflexible is a disciple of death. Whoever is soft and yielding is a disciple of life. The hard and stiff will be broken. The soft and supple will prevail.
It is our own mental attitude which makes the world what it is for us. Our thought make things beautiful, our thoughts make things ugly. The whole world is in our own minds. Learn to see things in the proper light.
Whatever I have tried to do in life, I have tried with all my heart to do it well; whatever I have devoted myself to, I have devoted myself completely; in great aims and in small I have always thoroughly been in earnest.