Why should I consider laughing when I feel so bad?

Because we laugh when we are hurt and laughter heals. The laughter was yours for the taking at birth. You used it then, and you can again. It's simply a matter of opening oneself to the healing powers of one's own body to assist in dealing with our painful emotions. We have to feel our emotions in order to heal. Our thoughts then assist our understanding. We need to feel as well as think in order to regain our balance so we can cope.