NO MATTER WHAT YOU DO, you can't avoid being exposed to pessimism. I remember when my son was born (26 years ago), for the first month or so I tried very hard to keep him uninfluenced by negativity or pessimism, and of course it was impossible. And he didn't even have conversations or watch television. All of us can (and should) do our best to keep ourselves from being exposed to unnecessary negativity, but if we're going to function in the world, we're going to be exposed to it.
You can counteract exposure to pessimism with positive input. And one excellent source of positive input is watching inspiring movies, especially true stories. And I have a great one to recommend. I just wrote an article about it on pantskicker.com. It's called Lorenzo's Oil.
Read the article here: Lorenzo's Oil: A True Story Of Determination.
If you pay attention, inspiring stories can not only make you feel good, they can be instructive. For example, one of the things you'll see in this movie is the mother going out of her way to get naysayers out of her sphere of influence. She was protecting herself from a pessimism infection, and in this case, her son's life depended on it.
Read the article and watch the movie. Your life will be richer for the time you spend.