Complex sentence: Feldman is an advocate for animal welfare and animal rights and has adhered to a vegetarian diet since he was about thirteen years old, and appeared with his wife in a PETA ad campaign promoting vegetarianism.
Split into simpler sentences: Feldman is an advocate for animal welfare and animal rights and has adhered to a vegetarian diet since he was about thirteen years old. He appeared with his wife in a PETA ad campaign promoting vegetarianism.