Yes that is absolute bollocks...that stupid suggestion to just will yourself to laughter. It can't be done, and even if it could, it would accomplish nothing.
Hmmm, let's see, I have a malady that doctors don't treat and often mock. My friends and family think I'm crazy. I had to leave my job, I haven't been laid in years, and I've lost many friends because I don't leave the house. My hair is falling out and I'm gaining weight around the middle.
But if I force myself to laugh out loud, all these things will clear up! Absolute b.s.
(disclaimer: only some of the above are my symptoms)