Consider how irregular my blogging is, and you will have some idea of how unsuccesful most of my attempts at daily journalling have been.
My life is highly resistant to attempts to impose routine upon it, but it has been known to happen – in restricted ways, and for limited times – in the past, but it's not something that comes easily. But almost nothing of any value is achieved without difficulty. Walking 900km in a foreign country will not be achieved without difficulty. So, if I can hike, on average 30km a day for 30 days, perhaps then I can also journal about those travels for 30 minutes at the end of each day.
Though a generalisation, my theory is that a person's life is either easy for them to write about, or worth writing about. I'd much rather have the former problem than the latter!