Answer:
This:
Dear Sarah,
I suddenly remembered my favorite day. It was when I was with my family in the zoo, where we had fun looking at animals we've never seen before! I saw a zebra, giraffe, and ostrich for the first time! How about you, though? What is your best day ever?
Sincerely,
[Your name]
That:
Dear Sarah,
I've started planning about my future. I thought about finishing high school, then going to college, then becoming a successful vet. I love animals, and I really love to take care of them. I want to have my own family, too! But right now, I have to do well in my studies so that I could achieve all of these. I'd love to hear about your plans, too.
Sincerely,
[Your name]