Running away isn't easy. What makes Winnie want to stay home in Tuck Everlasting?
Winnie realizes that, in actuality, "there's nowhere else (she) really (wants) to be" other than home. When it comes right down to it, she is afraid to go off on her own. She thinks,
"It's one thing to talk about being by yourself, doing important things, but quite another when the opportunity arises."
Through the characters that she reads about in books, and because of the constant warnings of her family, Winnie knows that the world is a dangerous place. She just feels that she "would not be able to manage without (the) protection" and security of home and those she loves. Although
"no one ever said precisely what it was that she would not be able to manage...she did not need to ask. Her own imagination supplied the horrors."
In essence, running away sounded really good to Winnie the day before, when she was so frustrated and angry at being an only child and the sole focus of her parents' and grandmother's constant nagging, but when she finally had an opportunity to make good on her resolve to run away and live life on her own terms, she found that she could not, because she was afraid.