You can't!! You can give them your arguments in favour of vegetarianism but they have to decide themselves whether they want to be vegetarian or not. Now pass the gravy, my steak's getting cold!! :))))))))))

Just hope for the next generation =p People need to be convinced but for their own reasons, not my reasons nor yours and in order to do that they need to understand what kind of commitment they are about to do (if they are willing to do it) So, I don't think we should convince people. You could show them the wonders of not hurting living things, which feels amazing or you could share websites, magazines, etc; you can also make them dinner so they can see that the quality of the food is the same (or "the same" ). And if after all you've done, they decide to keep up with their regular diet, that's ok too ^^. The glorious thing is that now they are making an informed choice because of the amazing job (in handing them the information) you did ! Smile anyways... your message will touch the right people and we will continue to spread the word (no religion involved!) without being worried about the results, just because we are happy to do it !

Why do you need this? I think someone who really want to be vegetarian should choose this way by himself.

These are the basic arguments in favour of vegetarianism and they can easily be found on the internet. 1) Eating meat is not at all required for health. There have never been any bulletins or recommendations saying that "we need to eat more meat (for health)". Not from the medical community (beholden to the pharmaceutical industry), not from health agencies (indebted to special interest groups). Not even the powerful meat industry has ever dared make such an outrageous claim. In fact, the converse is true: every recommendation you have ever seen always stresses that we need to eat less meat and more fruits and vegetables for our health. 2) There is no nutrient in meat that cannot be found in a vegetarian diet. No one can deny this. 3) There is no disease where eating meat is required for the treatment or cure of the disease. 4) Therefore, eating meat is absolutely unnecessary. 5) Eating meat causes death to other animals, obviously. And, despite attempts to make slaughter "humane", whether it be "kosher", "halal" or otherwise, it quite probably, or even certainly, causes stress and pain as well. 6) Therefore, eating meat is immoral and unethical. And abhorrently selfish, since the person who eats meat does so only for the hedonistic and temporary satisfaction of his taste buds. Especially when there are so many vegetarian and tasteful alternatives (from meatless and healthful soy products to traditional Indian dishes). 7) There is more than enough cruelty in the world as it is; no sane person can deny this. There is no need to add to the world's cruelty, unnecessarily.

Why would you want to convince him?