Every day of your life gets its own page so you can post a comment there.

Usually people write to their past selves regarding some regrets in order to ease the pain. Simply putting your thoughts out of the mind and onto the screen helps. And treating your past self as another person helps, too.

Also people write to their future selves to encourage/overcome the fear of the unknown.

You could write a message as if your past self would read it, and then maybe it will be read by the subprocess in your mind which continues to emulate your past self, which quietly and often secretly affects how your present self feels.

cough time travel

I use the schedule future email feature in Gmail it's nice to reflect on in the future my current fears/concerns at that time, am I still alive, etc...