When I tentatively began to keep a diary in April 1969, I could scarcely have imagined that decades of my life would not only be recorded but later published for all to see. I was 25 years old when I took a crisp new ring-backed notepad, headed the page “1969” and wrote, more in hope than expectation, “Thursday April 17th”. It was not actually my first attempt to keep a diary – so what did I think might be different that time?

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I lay a lot of the blame on our first son, Tom, who had been born six months earlier. He was a sweet, serious little fellow with a head as smooth as a billiard ball, and I loved nothing more than when he crawled into my arms and snuggled towards me.

Unfortunately I was a smoker at the time and Tom would immediately transfer his attention to the still warm butt in the ashtray. As all parents know, when you’re only six months old, just about everything is edible, so if he were to hug me without getting poisoned, I needed to give up. One evening when Terry Gilliam (a non-smoker) and my wife (also a non-smoker) accused me of helpless addiction, I finally made the decision. Somehow I lasted through the next day without one and the day after that too.

So surprised was I at this unprecedented exercise of willpower that, like a man reborn, I began to look around for other uses for my newly strengthened resolve.

I have always been attracted to lists, and the ultimate for any list keeper is to keep a record of what you’ve done each day. A diary, in fact. All I’d lacked in the past was the will to keep at it. Now here was a golden opportunity to try again, and to try properly.

Facebook Twitter Pinterest The (not so) secret diaries of Michael Palin, aged 72 ½. Photograph: David Levene/The Guardian

Very little happened on that first day of the new diary, or so it seemed at the time. Yet when I re-read my entry for Thursday 17 April 1969, my diary reminds me that I played squash, had David Jason round to lunch, walked over Hampstead Heath to Kenwood House, and took a phone call from David Frost about a rumour he’d heard that I was planning a new show with John Cleese. If I had not kept a diary I would never remember all this. And how unremarkable it seemed at the time. David Jason was a friend, not a television megastar, and Monty Python’s Flying Circus, the new show John had talked about, was still a glint in its mother’s eye.

That’s the attraction of a diary. It remains in its own time. It reflects only what happened on that particular day. It doesn’t flatter and it isn’t influenced by what happened later. In that way it’s the most truthful record of real life, and that’s why I’m so glad I persevered with it – writing an entry most mornings right up to today.

There are times when I’ve had to drive myself to do it. Times when I had so little time to write that I just jotted down a few notes, but mostly I’ve tried to approach each morning’s entry as a story of the day that’s just passed, without limits and without self-censorship. And composing a story a day is not a bad discipline for any would-be writer.

I never wrote with the idea of publication in mind. I don’t think I even wrote for another reader. The diary was more an aide-memoire than anything else. Occasionally I would read a piece to my wife, usually to settle an argument about what we had or hadn’t done. Otherwise, the family were far too busy with their own lives to be interested in mine.

But the longer I kept the diaries the more I saw them as accruing some sort of historical relevance. Something that happened the day before might have little significance at the time, but 25 or 30 years later it acquires an extra dimension. I have never regretted the decision to publish. It’s made me a little more self-conscious about what I write each morning, but I try my hardest to apply the same criteria to my entries as I’ve always done – what I did the day before.

Thanks to the diaries I can recollect things that I would almost certainly have forgotten – did I really think that A Fish Called Wanda was too nasty to be funny? Was I really scared stiff that Around The World In 80 Days could be a complete disaster? Well yes, the diaries prove it.

Facebook Twitter Pinterest Upside down you’re turning me ... Palin writes his diaries on one side of the page only, then turns and starts again. Photograph: David Levene/The Guardian

For a diarist life ceases to be an indistinct blur. Experiences are there in sharp focus; some an immeasurable pleasure, others a profound pain. Which is the way life is. And which is why diary-keeping is often prescribed as a therapy for those with depression, or those who feel their lives are somehow out of control.

I encourage you to do as I did all those years ago; get your own notebook out and write down the year and the day and what happened to you in the last 24 hours. And keep on doing it. I try and get down what I can remember in 30 minutes maximum – Alan Bennett warned me that if you’re not careful you start living for the diary, rather than the other way round.

I’ve found the diary habit very helpful to my own development as a writer. You have to be able to think clearly and edit as you go. An online blog is fine, but I feel very strongly that it’s not the same thing as writing down your own experiences in your own hand, in your own chosen notebook.

Handwriting is more personal. It expresses your personality. I can tell from mine how I was feeling at the time – sometimes hurried and rushed, sometimes relaxed and expansive. There are days when there are wine stains on the page, showing that I wrote the entry one evening, after a few.

You may find it hard, as I did, to find time to write. You may get discouraged by days when nothing seems to happen. Don’t give up. I’ve found that details of what you ate or who you were with or what music you were listening to might seem insignificant at the time but as the years go by these are the things you, and others, really want to know about. Tastes and circumstances change so fast that it is often hardly believable that this is what we did then, this is how we lived, this is what we all worried about. The diarist keeps tabs on us all.

Keeping a diary means that all that seeing and hearing, loving and laughing, excitement and embarrassment, gladness and gloom that go to make up a life are not forgotten. In short, a diary blows away the mists of time, and offers your life back to you.

Michael Palin’s 30 Years Tour starts 24 September; visit themichaelpalin.com. Guardian Live, an evening with Michael Palin, is on 2 November.

How to keep up the habit of writing a diary

Have it close to hand

I’d recommend something small: a smartphone or notebook. Keep your diary close, in your bag or laptop bag. If your diary is to be a home-bound creature, keep it under your bed or in your bedside drawer. Don’t let it stray too far from you in case of fire (think Pepys) and diary snoops.

Be spontaneous

Not everything we jot down needs to be carefully thought out. It can also be a place where we think carelessly, loosely – “slovenly” as Woolf phrased it. We can write our diaries in a state of semi-undress – literally and creatively.

Make it daily

Diary-keeping is a mild to moderate religion. It needs commitment and some degree of organisation. Virginia Woolf reserved an hour or two post-teatime to write hers. One friend of mine wrote hers for years while her daughter napped. Ask yourself when you are most likely to keep one. Perhaps on the train home, or on the loo (why not?), before you get dressed in the morning, or before you go to sleep.

Don’t be scared

Diary-writing takes courage. In our digital culture we have become frightened of paper. What we write down seems more final, more resolute. But make the effort and it can offer a crucial moment of reflection. It’s actually a form of mindfulness – a process of peacefully observing what’s running through your mind.

Tips by diary expert Sally Bayley, author of The Private Life of the Diary