Notice your natural experience of "I," as in "I want this," "I do not want that."
Recognize that it is natural to want happiness and to not want pain. This is valid, and does not require further justification.
Based on this natural desire, you have the right to obtain happiness and to get rid of suffering.
Just as you have this right, so do others, and in equal measure.
Consider the fact that the difference between yourself and others is only that you are just one single person, whereas there are countless other living beings on this planet alone.
Pose this question: Should I use every living being to attain my happiness, or should I help others gain happiness?
Imagine yourself, calm and reasonable, looking to your right at another version of yourself – but this self is overly proud, never thinking of the welfare of others, concerned only with her or her own self.
On your left, visualize a number of destitute people unrelated to you, in need and in pain.
You, in the middle, are an unbiased, sensible person. Consider that those people on both sides of you want happiness and want to get rid of pain; in this way, they are equal, the same.
But think: The selfishly motivated person on the right is just one person, whereas the others are far greater in number. Which side is more important, the one with the single, self-centered person, or the vast group of poor, helpless people?
To which side will you devote your energies? As the unbiased person in the middle, you will naturally favor the greater number of suffering people.
Reflect on this thought: If I, as just one person, take advantage of the many, it would be truly contrary to my humanity, and to common sense. To sacrifice a lot for the sake of a little is foolish.
Thinking this way, you will decide: I am going to direct my energies to the many rather than to this one selfish person.