A trade log records prices. A behaviour journal records the decisions around them: why you entered, what you felt, what you were doing immediately before, whether you followed each rule, and what you would change.
The fields that pay are the ones nobody wants to fill in. Hours slept, stress level, whether the trade was planned before the session, whether you had just lost, and a plain grade for execution. After a few months these columns explain most of the variance in your results, usually more than any market variable.
Use it for behaviour change rather than for reminiscing. Pick one recurring error from the last twenty trades, write a single if-then rule for it, and review that one rule next week. See implementation-intention.
Related: trading-journal, post-trade-review, process-goals, tilt-triggers