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: @CornerBakery Sorry I missed you :) I stayed up late working and pondering life
This tweet contains emotions: 
sadness