Task: Classify the mental state of the tweeter based on the tweet, determining if it is 'neutral or no emotion' or characterized by any of the provided emotions (anger, anticipation, disgust, fear, joy, love, optimism, pessimism, sadness, surprise, trust).
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