Problem: Continue the following story.

Kevin had to take a daily vitamin D supplement but Justin did not because 
Here's how I want to continue it: Kevin did not get enough sunshine.

Problem: Continue the following story.

Christine  reminded Sarah to feed the goldfish because 
Here's how I want to continue it: Christine was going out of town.

Problem: Continue the following story.

Samantha excelled in ballet while Tanya was terrible at it. 
Here's how I want to continue it:
Tanya had always been clumsy with bad balance.