People are books. More accurately, people are like books. This can be a useful simile overall, whether applied to friends and family members, or to a new relationship or conversation.
Some books are required reading. Even if you don't enjoy those books, commitment is in your best interest.
Some books look like great fun, but end up being a waste of time.
Most books are somewhere in between. If you pick up a new book, especially if you paid for it, you will probably try your best to enjoy it. Most people approach voluntary reading with an open mind and sense of curiosity. The contents of the book are ripe for discovery. Even if it doesn't become your favorite book, you'll have a more enriching experience if you focus on what you enjoy about the book, rather than entering as a critic.
Of course, like any simile, this one isn't perfect. People do not exist for your entertainment, and no book actually requires your attention or benefits from your involvement in their existence. In other words, thinking of people as books is not to illustrate the balance of giving and receiving. It is to illustrate a mindset of willingness. On the other hand, some books really are not worth finishing, and there are some people who have no place wasting your time. You just can't judge that, as the saying goes, by the cover.
A lot of people don't even like books at all anymore. Those people are missing out on a lot!
If you would give a book a chance, give a person a chance.
Try approaching your next conversation with the same curiosity and eagerness to learn and discover as you would a brand new book.