I have a Google Sheets … sheet? … for this, and it's been handy.
I'm paper trading the stock market while I work on a couple of investment ideas (and still feel like I'm learning, so no real money yet). Every time I "buy"/"sell" a stock (logged in one tab of Google Sheets), I enter the date and the rationale I used when making the decision (logged in another tab of the same Sheet), as well as some context around the current state of the world. It's been useful already (a few months in), but will only get more useful, I believe, as I begin to note patterns in my own behavior.
I'm paper trading the stock market while I work on a couple of investment ideas (and still feel like I'm learning, so no real money yet). Every time I "buy"/"sell" a stock (logged in one tab of Google Sheets), I enter the date and the rationale I used when making the decision (logged in another tab of the same Sheet), as well as some context around the current state of the world. It's been useful already (a few months in), but will only get more useful, I believe, as I begin to note patterns in my own behavior.