alt Hacker Newsi would say, be generous with yourself in terms of tracking showing up at all since that alone is huge (and most important for sustaining the behavior). if you notice that you're slipping and showing up late too often, maybe create another habit for being on time?
i don't understand the rationale behind cheating one's own self improvement journal. what's the end game?
Self-destruction, via small acts of self-sabotage.
Next day, your inner critic and saboteur tell you something along the lines of: "You shouldn't go today - you're tired, there's so much work that you should do instead, and you're not even doing the gym actually/properly (AGAIN), just look at yesterday, you couldn't even do 25 min, you've cheated and have now tainted it". Even though it was the same exact voice that led you to do it yesterday.