When you are discontent, you always want more, more, more. Your desire can never be satisfied. But when you practice contentment, you can say to yourself, 'Oh yes - I already have everything that I really need.'
We find that the more a cultivated reason devotes itself to the aim of enjoying life and happiness, the further does man get away from true contentment.
Material objects give rise to physical happiness, while spiritual development gives rise to mental happiness. Since we experience both physical and mental happiness, we need both material and spiritual development. This is why, for our own good and that of society we need to balance material progress with inner development.
If a person's basic state of mind is serene and calm, then it is possible for this inner peace to overwhelm a painful physical experience. On the other hand, if someone is suffering from depression, anxiety, or any form of emotional distress, then even if he or she happens to be enjoying physical comforts, he will not really be able to experience the happiness that these could bring.