Rather than only answering mindful questions (either pre-generated or customized) after a meal, you also have the opportunity to record answers right as a meal photo is captured.
To choose which pre-meal questions should be displayed:
Go to Profile > Settings.
Scroll down to More > Meal Q&As.
Select the particular question.
Turn on the pre-meal toggle.
Save at the bottom.
From here, when a meal image is captured, this particular pre-meal question will pop up as well.