I wanted to maintain a diary (I call it a journal) since I was a teenager. The reason was simple. I wanted to be a writer, and everywhere I read that this was a crucial step. For many years, it was only easy to do when I was traveling. But, about six years ago, I committed to writing every day, and clocked myself for a year. Since then, though I can't say I write in my journal every day, it's probably quite close - well over 300 days a year. I strongly recommend this for anyone who wants to become a better writer. There are many ways of writing in a diary or journal - find what works for you. If you're not sure where to start, check out the beginning of The Artists Way by Julia Cameron, and try morning pages. They work for my wife. It's not exactly what I do now, but it's a great approach.