It was nice to get your letter! I'm sorry to hear about your friend's diet and her vegetarianism. It sounds like she's very determined.
To answer your questions: People become vegetarians for many reasons. Some do it for health, others for ethical reasons concerning animal welfare, and some for environmental concerns. It's a personal choice, but it's true that a balanced vegetarian diet requires careful planning to ensure all nutritional needs are met.
As for me, I try to stay fit by exercising regularly, mainly through jogging and some yoga. I also aim for a balanced diet, though I'm not vegetarian. I try to avoid excessive amounts of processed foods and sugary drinks. When it comes to food I try to avoid, I generally limit my intake of fried foods and large portions of red meat.
I hope your friend finds a healthy way to achieve her goals.
Best wishes,
[Your Name]