Determine the emotional tone of the following tweet: "Yesterday is history, tomorrow is amystery, and today is a gift; that's why they call it the present #livelife #humbleness  #live". Use the provided emotions: anger, anticipation, disgust, fear, joy, love, optimism, pessimism, sadness, surprise, trust. Respond with the emotions you identify or "neutral or no emotion".
joy, optimism