When you are unhappy, is there anything more maddening than to be told that you should be contented with your lot?
Life is easier than you'd think; all that is necessary is to accept the impossible, do without the indispensable, and bear the intolerable.
Before you begin a thing, remind yourself that difficulties and delays quite impossible to foresee are ahead. If you could see them clearly, naturally you could do a great deal to get rid of them but you can't. You can only see one thing clearly and that is your goal. Form a mental vision of that and cling to it through thick and thin.