Laughter provides natural stress relief, releasing anger, tension, fear and guilt. If your laugh has changed over the years, you need to change your laugh for your next production, or you simply do not like your laugh, you can change it with practice and repetition. Once you find a laugh that you would like to mimic, prepare to spend time repeating it until you can naturally laugh just like it.
Find a laugh that you would like to mimic. Pick the laugh of a person you know or possibly someone in a movie.
Using a voice recorder, record the laugh that you would like to mimic.
Play the sound file and mimic it to the best of your ability. Repeat this step throughout your day until you think you can laugh on your own without listening to it.
Try laughing without listening to the sound file. Eventually your new laugh will come naturally to you.
You can change your laugh as often as you like.
Pay attention to your laugh to notice if it starts to change back. Some people mimic the laugh of people they keep for company.