Why did you make this mental bet?
You need to be able to articulate that, and then remember that.
Never forget...
"Keep track of your bets and why you made them." --KVB
One could argue that it is more important to track a mental bet than an actual bet. Regardless of your stance, tracking mental bets is extremely important.
After all, there is no need to make a mental bet if you aren't tracking the results and why you made it. It is literally the purpose of a mental bet.