I corresponded with someone by e-mail for just over a decade. At the beginning, we wrote every few days and then it became daily. We talked about ideas, told stories about our pasts, and, if anything interesting was going on, we were reading a good book, had heard a great piece of music, had read a funny sign, had a strange conversation in the supermarket, or even just the dailiness of life, we wrote about it, every day.
That's the closest thing to consistently maintaining a journal or a diary that I have. It's a fantastic record of what went on in my life for that span of time. It was far easier, I found, to frame ideas and thoughts and life within the context of a conversation, rather than writing into a book or creating pixels to save in an electronic file that didn't ever provoke further thought. And I forget quite a lot of incidents and things that happened and notions that amused or entertained me, until I go back and read them. Then I'm very glad to have written it all.