A Potential Approach

There are multiple ways to approach making something that is more happy and lighthearted.

One way I can imagine is to use humor. There are many sayings out there saying that the best cure for sadness is laughter. Even some of the more serious topics like World War 2 can be made funny with a well placed joke or play on words.

Another way is to try to be happy yourself when you write. Our written works are often a reflection of our own feelings and it would probably be much easier to write something lighthearted if you try to fill your mind with comfortable thoughts.

Those are a couple of suggestions I have. I really hope that these ideas are helpful to you in your pursuit to write happier things!