Metta or loving-kindness meditation is my absolute favorite!

Aloud or to self with eyes closed or staring at a candle flame, say:

May I be well, may I be happy, may I be free from suffering.

then think of someone you are close to and send them these words,

May you be well, may you be happy, may you be free from suffering.

then think of someone you know who might need your words,

May you be well, may you be happy, may you be free from suffering.

then think of someone you are not on good terms with or resent,

May you be well, may you be happy, may you be free from suffering.

then include the whole world,

May we be well, may we be happy, may we be free from suffering.