This quote means we have a decision to make when things happen – do we react with anger or with a positive attitude? "This is our choice in every moment" is like saying we can decide how to feel. It's up to us.
Think of it like picking a flavor of ice cream. "This is our choice in every moment" is like choosing between chocolate or vanilla. When something happens, we can choose to be upset (bitterness) or to be okay with it (openness).
In simple words, this quote tells us that when things happen, we can choose to be angry or to be understanding. It's like picking how we want to feel about what's going on. Just like we choose our favorite ice cream, we can choose our attitude towards situations.