Force yourself to smile. If you are alone,force yourself to whistle or hum a tune or sing. Act as if you were already happy,and that will tend to make you happy.

• 强迫你自己微笑，如果你单独一人的时候，吹吹口哨，唱唱歌，尽量让自己高兴起来，就好象你真的很快乐一样，那就能使你快乐。