In order to perform karma yoga, there is a simple general principle to keep in mind: bring a third component into every action. If, for example, you are digging a ditch, there is you who is digging the ditch, and the ditch which is being dug. Now add a third focus: say, a disinterested person who is seeing you dig the ditch. Now run the entire action through his head while you are digging. It’s as simple as that. Through this method you would ultimately free yourself from identifying with him who is digging the ditch. You would merely see a ditch being dug.