Find a reason for living.
Put a smile on your face,
And a song in your heart.
Make others happy.
Get away from yourself.
Get involved with other people.
Don't do the 3 c's:
(The foregoing was heard in a shiur by Aharon Romm.)
Psalm 27 says: "Hope for the Lord, be strong and He will give your heart courage, and hope for the Lord."
The first step is always ours and then Hashem meets us where we are. We make the decision to be happy, even if we don't feel it and the feeling will follow.