Task: Analyze the tweet's sentiment and assign it to either 'neutral or no emotion' or one or more of the specified 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