I keep a basic diary. Every evening I jot down a couple of lines in shorthand. It helps me to visualise the passing of time. If I don't feel like the time is just disappearing, I feel more in control of it, which means I make more conscious decisions about what to do with it. The trick is to write down what I've done and not what I need to do, so it doesn't become a to-do list (i.e. a source of anxiety). Once a week I do a short summary.
The diary also contains my goals for the year (5 or so) and a list of life areas that are important to me (work/learning/relationships/etc.). Once a month I write a monthly summary: I look back and compare my weekly summaries to the last month's summary and the annual goals. I see where in the different life areas I need to focus next.
Sometimes I'll start a list elsewhere in the book and track something for a while. I have tracked my moods when I wanted to see patterns and I have a list for cleaning I do around the house, a list of new vocabulary items I've picked out of books I read, etc.
I also use a calendar built into my e-mail to track appointments/birthdays. Once a month I have scheduled a mental health check-in with myself, whereby I go through some self-therapy.
Leonard Cohen (Bird on a Wire): I have tried in my own way to be free
Mrs Hudson (BBC Sherlock): Sherlock! The mess you've made!