Deep rest is the essence of sadhana. You have become so tired by doing something or the other all the time. Now just sit down for some time and to be with yourself. Do some meditation. When you meditate, you will start seeing a new world in front of you.
You get deep rest is meditation. You get rest when you are content, and this rest is what gives rise to Happiness.
Running behind happiness makes you tired. When you run behind happiness you get tired, but when you repose in the self, when you rest, you get energy, and that brings you strength, joy and happiness. So every once in a while, stop the rat race, and take some time out to be with yourself, and get some rest. This is what knowledge is and this is what spirituality is.
Many time, in the name of sadhana also, we start engaging ourselves in some activity, and once again we get tired. I tell you, the physical body does not make you as tired as the mind does. Work doesn’t make you as tired as much as your desires. Nothing else makes you more tired than your own desires, or greed. So what is important is for you to become content. Again and again, be content. This is an art and this is what meditation is. True sadhana is to being calm, contented, and rested.