Before I get into this, please understand: I am not a doctor. In any way. If I had a PhD, it would probably be in English or History, not medicine. But I do have an active interest in people’s attitudes and how it plays into their overall physical health.
I know when I was a kid and not feeling well, my dad would always put on a funny movie for me like the Indiana Jones trilogy. It was something that stuck with me all these years. Now, when I’m not feeling well, I instinctively want to watch something funny or do something low key that makes me happy (like cross stitch or write or read a good book). Part of it could be the distraction, and there are others who believe there is a legitimate health benefit to it all .
But, I have my own theories as to why it actually helps your physical health.
1. The distraction aspect—our minds are powerful things. Whatever we think about most grows the most. Ever think of a negative problem so much it became a huge issue in your life? Same goes with the good stuff. If you focus on the good things, those will become the largest parts of your life.
2. The attitude aspect—it’s a known fact that people who are bitter and negative tend to develop serious health issues from arthritis to heart issues from the added stress in their lives. Being a positive person, while not preventing every disease out there, can improve your chances of missing big ones like heart issues, stress related illness, and other preventable problems.
3. Laughing burns calories—no, this isn’t wishful thinking. There are studies  that show that ten to fifteen minutes of laughter a day can burn ten to forty calories a day (which could translate into roughly four pounds a year). Now there’s something to get happy about.
4. Enjoying your life means a better lifestyle—when you genuinely enjoy your life and what you do, you are more likely to take better care of that life. You’ll take the necessary steps to make your life stays enjoyable and you’ll actively seek opportunities to find joy on a daily basis.
Regardless of why you laugh, it’s definitely easier than a lot of other methods to get happy or get healthy. While it won’t cure all your troubles, it’s definitely a start.