Zen and the art of wood carving.
A task, in which I am fully concentrated on, is something I find very meditative. At some point I lose track of time, then track of thoughts, track of my surroundings even.
A man sitting with his legs crossed on a flat piece of wood under a shadow cast into the ground by a small tree. There are twelve medium-sized sticks by his side, a handaxe and a blunt kitchen knife whose days of glory are but long gone. The man's aim is to carve a sharp end to one end of each stick, to drive them successfully into the ground for a gardening fence. He sits down, grabs the axe where the blade resembles a Neanderthal-like rock rather than a stainless steel edge of a tool. The task seems impossible but he decides to put all of his mind into it - a strange dedication for a simple purpose. He starts chopping small pieces off from the end of a stick, leaning the piece of wood against a red brick, with the axe. The progress is slow and sometimes he has to use the knife to smoothen the surface of the stick. Little by little the stick starts to obey the axe and its master, and changes warily its form into a spearlike object.
When sharpening his fourth stick, the man notices that it is, in fact, the fourth stick already. Time doesn't seem relevant and he can't remember any of his thoughts for the past fifteen (twenty?) minutes. His right hand aches from all the work but little did he notice the pain when his hand was flinging the axe. Only when he stopped and lost his concentration, did he notice that he has been using muscles for the job, not only his mind.
The man feels relaxed, and somehow satisfied. In front of him, four wooden sticks with sharp ends. Not a breakthrough in any science, not a victory in any war, but a thorough feeling of wellbeing and peace of mind.
A simple task, which takes some effort, requires some concentration and doesn't wear you out too much. Do it for a while with a small goal, some form of achievement to be reached, and notice how much more you feel yourself enjoying your feelings.