Task: Identify the primary emotion conveyed in the tweet and assign it to either 'neutral or no emotion' or one or more of the provided emotions (anger, anticipation, disgust, fear, joy, love, optimism, pessimism, sadness, surprise, trust) that best capture the tweeter's mental state.
Tweet: A #smile doesn't always mean a person is #happy . Sometimes it simply means they are #strong enough to face their own #problems .
This tweet contains emotions: 
joy, optimism, sadness