A delta file is traditionally your little black book of every behaviour you see that makes you think “I hope I never do that”, but I extend it to noting great behaviours I want to emulate.
Here’s four examples to start you going. Get a book — a nice one that you can keep for a few years — and record them in that. The entire purpose of this book is to maintain your Delta File. If you use a general notebook, you’ll lose your Deltas.
- Find a way to say ‘yes’ when you feel like saying ‘no’. “We could do what you propose if first we do X”
- Don’t interrupt meetings for water-cooler chat
- Don’t set deadlines that are meaningless
- Don’t expect a direct to honor a commitment to you if you don’t honor yours to them
Here’s what you don’t put in the Delta File:
- Bob is a hypocrite who expects us to wash up, but doesn’t do his own dishes
- Try not to be so blah
Number 1: if you write this down, Bob is certain to somehow end up reading your Delta File.
Number 2: What is blah? What will it mean when you read this in two years time?
But what do you do with it?
This file is your pre-training for your next promotion, or for your next New Years Resolutions. The simple act of writing them down will help you remember in the short term, but you’ll be amazed at what you find in the book in two years time.
Bonus Tip
This book doesn’t need to just be about work. Record behaviours you see from your friends and family that you either want to emulate or avoid. Again, don’t mention who caused you to write it down for obvious reasons!

