The following quotes and passages come from the pen of the Roman Stoic philosopher Lucius Seneca.

Each day, too, acquire something which will help you to face poverty, or death, and other ills as well. After running over a lot of different thoughts, pick out one to be digested thoroughly that day. This is what I do myself; out of the many bits I have been reading I, lay hold of one. My thought for today is something which I found in Epicurus (yes, I actually make a practice of going over to the enemy‟s camp – by way of reconnaissance, not as a deserter!). „A cheerful poverty,‟ he says, „is an honourable state.‟ But if it is cheerful it is not poverty at all. It is not the man who has too little who is poor, but the one who hankers after more. What difference does it make how much there is laid away in a man‟s safe or in his barns, how many head of stock he grazes or how much capital he puts out at interest, if he is always after what is another‟s and only counts what he has yet to get, never what he has already. You ask what is the proper limit to a person‟s wealth? First, having what is essential, and second, having what is enough.

– Lucius Seneca, On The Shortness Of Life

The great blessings of mankind are within us, and within our reach; but we shut our eyes and, like people in the dark, we fall foul upon the very thing we search for without finding it. Tranquility is a certain equality of mind, which no condition of fortune can either exalt or depress. Nothing can make it less, for it is the state of human perfection: it raises us as high as we can go; and makes every man his own supporter. Whereas he that is borne up by anything else may fall. He that judges aright, and perseveres in it, enjoys a perpetual calm: he takes a true prospect of things; he observes an order, measure, a decorum in all his actions; he has a benevolence in his nature; he squares his life in accordance with reason; and draws to himself love and admiration: but he that always wills or nills the same things is undoubtedly in the right. Liberty and serenity of mind must necessarily ensue upon the mastering of those things which either allure or affright us when, instead of those flashy pleasures (which even at the best are both vain and hurtful together), we shall find ourselves possessed of joy transporting and everlasting.

– Lucius Seneca, On The Happy Life

Finally, everybody agrees that no one pursuit can be successfully followed by a man who is preoccupied with many things—eloquence cannot, nor the liberal studies—since the mind, when distracted, takes in nothing very deeply, but rejects everything that is, as it were, crammed into it. There is nothing the busy man is less busied with than living: there is nothing that is harder to learn.

– Lucius Seneca, On The Shortness Of Life