I do enjoy reading the motivational quotes of others. I never pay them any mind, Your motivations will be your own. It really does not matter what "Mark Twain" or Shakespeare" said, what I or others suggest, You will make your own life and only you will know that you are happy with it. Though I suspect that no one is truely happy. Anyway here is one for you. I just came up with it out of the blue.
Hmmm, "But we are full of everything. Not only organs, bones, sinews and muscles but of life itself. We are filled with thoughts, ideas, emotions, empathy, disgust, frivolity, perspecation. "The human is never empty, rather a roiling brew of substance that it takes a lifetime to understand. The only folly is that some give up too soon".