It's wrong to lie to people about what you're doing.
Lydia is relaxing at home after a very busy week when her sister calls her to ask if she wants to spend the day with her.
Lydia wants to spend the day alone.
Lydia tells her sister that she is tired and needs to spend some time alone to rest.
Lydia tells her sister she already has plans with some friends for the day.
Lydia's sister understands and happily plans something with her for next weekend instead.
Lydia's sister eventually finds out that Lydia did not tell the truth and is saddened by it.