I quit animal products pretty abruptly and on a personal level I wouldn't say doing it all at once is necessarily the difficult part. I was unprepared for the sudden lop-sidedness in favour of needing to plan and prepare meals. The shift to not being able to eat unprocessed on-the-go and restaurant meals because the plant-based options were mediocre to non-existent is quite drastic. I've gotten used to accompanying people who are eating without partaking myself.